SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                 FORM 10-K / A-1


|X|      ANNUAL  REPORT  PURSUANT  TO  SECTION  13 OR  15(d)  OF THE  SECURITIES
         EXCHANGE ACT OF 1934 - For the fiscal year ended December 31, 1999

                                       OR

|_|      TRANSITION  REPORT  PURSUANT  TO SECTION 13 OR 15(d) OF THE  SECURITIES
         EXCHANGE ACT OF 1934

                          Commission file number 1-640

                               NL INDUSTRIES, INC.
- --------------------------------------------------------------------------------
             (Exact name of registrant as specified in its charter)

          New Jersey                                              13-5267260
- -------------------------------                              -------------------
(State or other jurisdiction of                                 (IRS Employer
 incorporation or organization)                              Identification No.)

16825 Northchase Drive, Suite 1200, Houston, Texas               77060-2544
- --------------------------------------------------           -------------------
   (Address of principal executive offices)                      (Zip Code)

Registrant's telephone number, including area code:             (281) 423-3300
                                                             -------------------

Securities registered pursuant to Section 12(b) of the Act:

                                                        Name of each exchange on
      Title of each class                                    which registered
- ------------------------------                          ------------------------
Common stock ($.125 par value)                           New York Stock Exchange
                                                         Pacific Exchange

Securities registered pursuant to Section 12(g) of the Act:  None.

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the  preceding 12 months,  and (2) has been subject to such filing  requirements
for the past 90 days.     Yes X            No

Indicate by check mark if disclosure of delinquent  filers  pursuant to Item 405
of Regulation  S-K is not contained  herein,  and will not be contained,  to the
best of registrant's  knowledge,  in definitive proxy or information  statements
incorporated by reference in Part III of this Form 10-K or any amendment to this
Form 10-K. |X|

The  aggregate  market value of the voting stock held by  non-affiliates  of the
registrant at March 16, 2000 approximated $167 million.

There were 50,629,740 shares of common stock outstanding at March 16, 2000.

                      Documents incorporated by reference:

The  information  required by Part III is  incorporated  by  reference  from the
Registrant's  definitive  proxy  statement to be filed with the  Securities  and
Exchange Commission pursuant to Regulation 14A not later than 120 days after the
end of the fiscal year covered by this report.


The undersigned Registrant hereby amends the following items, financial statements, exhibits or other portions of its Annual Report on Form 10-K for the year ended December 31, 1999 as set forth below and in the pages attached hereto: Item 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K. Exhibit No. 99.1, Annual Report of NL Industries, Inc. Retirement Savings Plan on Form 11-K for the year ended December 31, 1999 (filed as an amendment to the Registrant's Annual Report on Form 10-K for the year ended December 31, 1999).

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this amendment to be signed on its behalf by the undersigned, thereunto duly authorized. NL INDUSTRIES, INC. ----------------------------- (Registrant) Dated: June 27, 2000 By: /s/ Robert D. Hardy ----------------------------- Robert D. Hardy Vice President and Controller


                                                                    Exhibit 99.1



                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                    FORM 11-K


                 Annual Report Pursuant to Section 15(d) of the
                         Securities Exchange Act of 1934


|X|        Annual report  pursuant to Section 15(d) of the  Securities  Exchange
           Act of 1934 - for the year ended December 31, 1999

                                       or

|_|        Transition  report  pursuant  to  Section  15(d)  of  the  Securities
           Exchange Act of 1934 - for the transition period from       to

                          Commission file number 1-640


           A. Full title of the plan and the address of the plan,  if  different
from that of the issuer named below:

                               NL INDUSTRIES, INC.
                             RETIREMENT SAVINGS PLAN

           B. Name of issuer of the securities held pursuant to the plan and the
address of its principal executive office:

                               NL INDUSTRIES, INC.
                       16825 Northchase Drive, Suite 1200
                            Houston, Texas 77060-2544





NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN INDEX Page Signature Page 2 Financial Statements and Supplemental Schedules with Report of Independent Accountants F-1 to F-15 Exhibit I - Consent of Independent Accountants - 1 -

SIGNATURE Pursuant to the requirements of the Securities Act of 1934, the Administrator has duly caused this Annual Report to be signed by the undersigned thereunto duly authorized. NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN By: NL INDUSTRIES, INC. PENSION AND EMPLOYEE BENEFITS COMMITTEE, Administrator of NL Industries, Inc. Retirement Savings Plan By: /s/ Robert D. Hardy Robert D. Hardy Chairman, Pension and Employee Benefits Committee June 27, 2000 - 2 -

NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN FINANCIAL STATEMENTS, FUND INFORMATION AND SUPPLEMENTAL SCHEDULES WITH REPORT OF INDEPENDENT ACCOUNTANTS December 31, 1999

NL INDUSTRIES INC. RETIREMENT SAVINGS PLAN INDEX Page Report of Independent Accountants F-2 Financial Statements: - --------------------- Statements of Net Assets Available for Benefits - December 31, 1998 and 1999 F-3 Statements of Changes in Net Assets Available for Benefits with Fund Information - Years ended December 31, 1998 and 1999 F-4 to F-7 Notes to Financial Statements F-8 to F-13 Supplemental Schedules: - ----------------------- Schedule of Assets Held for Investment Purposes at End of Year - December 31, 1999 F-14 Schedule of Reportable Transactions - Year ended December 31, 1999 F-15 All other schedules are omitted because they are not applicable or not required. F-1

REPORT OF INDEPENDENT ACCOUNTANTS To the Pension and Employee Benefits Committee of NL Industries, Inc.: In our opinion, the accompanying statements of net assets available for benefits and the related statements of changes in net assets available for benefits present fairly, in all material respects, the net assets available for benefits of the NL Industries, Inc. Retirement Savings Plan (the "Plan") at December 31, 1998 and 1999, and the changes in net assets available for benefits for the years then ended in conformity with accounting principles generally accepted in the United States. These financial statements are the responsibility of the Plan's management; our responsibility is to express an opinion on these financial statements based on our audits. We conducted our audits of these statements in accordance with auditing standards generally accepted in the United States, which require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for the opinion expressed above. Our audits were conducted for the purpose of forming an opinion on the basic financial statements taken as a whole. The supplemental schedules, as listed on the accompanying index, are presented for the purpose of additional analysis and are not a required part of the basic financial statements but are supplementary information required by the Department of Labor's Rules and Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of 1974. The fund information in the statements of changes in net assets available for benefits is presented for purposes of additional analysis rather than to present the changes in net assets available for benefits of each fund. These supplemental schedules and fund information are the responsibility of the Plan's management. The supplemental schedules and fund information have been subjected to the auditing procedures applied in the audits of the basic financial statements and, in our opinion, are fairly stated in all material respects in relation to the basic financial statements taken as a whole. PricewaterhouseCoopers LLP Houston, Texas June 8, 2000 F-2

NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN STATEMENTS OF NET ASSETS AVAILABLE FOR BENEFITS December 31, 1998 and 1999 1998 1999 ----------- ----------- ASSETS Investments at fair value: Common stock ............................... $ 2,347,862 $ 2,429,229 Other securities ........................... 23,406,941 23,331,334 Employer contributions receivable ............ 598,532 307,458 Cash ......................................... -- 36,427 ----------- ----------- Net assets available for benefits .......... $26,353,335 $26,104,448 =========== =========== See accompanying notes to financial statements. F-3

NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS WITH FUND INFORMATION Year ended December 31, 1998 Fund Information ----------------------------------------------------------- AIM MFS Emerging Templeton International AIM Value Growth Fund World Fund Equity Fund Fund ------------ ---------- ------------- --------- Additions: Investment income: Net appreciation (depreciation) in the fair value of investments ................................. $ 354,126 $ (85,801) $ 46,443 $ 420,196 Dividend income: NL Industries, Inc. ........................... -- -- -- -- Halliburton Company ........................... -- -- -- -- Dresser Industries ............................ -- -- -- -- Tremont Corporation ........................... -- -- -- -- Other ......................................... 11,692 132,397 5,780 62,572 Interest income ................................. -- -- -- -- ----------- ----------- ----------- ----------- Total investment income ......................... 365,818 46,596 52,223 482,768 ----------- ----------- ----------- ----------- Contributions: Participants .................................... 65,968 29,445 40,487 78,531 Employer ........................................ 45,032 24,465 19,677 59,013 ----------- ----------- ----------- ----------- Total contributions ........................... 111,000 53,910 60,164 137,544 ----------- ----------- ----------- ----------- Total additions ................................. 476,818 100,506 112,387 620,312 Deductions - distributions .......................... 46,915 8,701 29,944 129,760 Net interfund transfers ............................. (59,634) (957,929) (34,577) (1,125,860) ----------- ----------- ----------- ----------- Net increase (decrease) ............................. 370,269 (866,124) 47,866 (635,308) Assets transferred to another plan .................. (923,408) (278,015) (183,021) (727,621) Net assets available for benefits: Beginning of year ................................. 1,876,572 1,783,781 422,276 2,449,561 ----------- ----------- ----------- ----------- End of year ....................................... $ 1,323,433 $ 639,642 $ 287,121 $ 1,086,632 =========== =========== =========== ===========

Fund Information -------------------------------------------- ML Global MFS Government ML Equity Allocation Securities Fund Index Trust Fund, Inc. --------------- ----------- ----------- Additions: Investment income: Net appreciation (depreciation) in the fair value of investments ................................. $ 7,294 $ 333,231 $ (11,565) Dividend income: NL Industries, Inc. ........................... -- -- -- Halliburton Company ........................... -- -- -- Dresser Industries ............................ -- -- -- Tremont Corporation ........................... -- -- -- Other ......................................... 21,304 -- 28,954 Interest income ................................. -- -- -- ----------- ----------- ----------- Total investment income ......................... 28,598 333,231 17,389 ----------- ----------- ----------- Contributions: Participants .................................... 13,359 38,208 22,453 Employer ........................................ 12,398 36,780 18,762 ----------- ----------- ----------- Total contributions ........................... 25,757 74,988 41,215 ----------- ----------- ----------- Total additions ................................. 54,355 408,219 58,604 Deductions - distributions .......................... 3,206 46,079 21,963 Net interfund transfers ............................. (64,127) (142,787) (173,518) ----------- ----------- ----------- Net increase (decrease) ............................. (12,978) 219,353 (136,877) Assets transferred to another plan .................. (138,924) (1,291,724) (225,360) Net assets available for benefits: Beginning of year ................................. 435,437 1,571,231 630,476 ----------- ----------- ----------- End of year ....................................... $ 283,535 $ 498,860 $ 268,239 =========== =========== =========== F-4

NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS WITH FUND INFORMATION (CONTINUED) Year ended December 31, 1998 (Continued) Fund Information (Continued) ------------------------------------------------------------------------------------ ML Federal ML Capital ML Basic ML Retirement Mercury Global Securities Fund, Value Preservation Holdings, Trust Inc. Fund Trust Inc. ----------- ---------- -------- -------------- -------------- Additions: Investment income: Net appreciation (depreciation) in the fair value of investments ... $ 1,923 $ 188,576 $ 316,966 $ -- $ 45,144 Dividend income: NL Industries, Inc. ............ -- -- -- -- -- Halliburton Company ............ -- -- -- -- -- Dresser Industries ............. -- -- -- -- -- Tremont Corporation ............ -- -- -- -- -- Other .......................... 29,733 176,522 229,209 -- 41,011 Interest income .................. -- -- -- 1,002,946 -- ------------ ------------ ------------ ------------ ------------ Total investment income .......... 31,656 365,098 546,175 1,002,946 86,155 ------------ ------------ ------------ ------------ ------------ Contributions: Participants ..................... 25,955 87,075 133,404 100,027 -- Employer ......................... 29,422 71,739 136,427 99,794 -- ------------ ------------ ------------ ------------ ------------ Total contributions ............ 55,377 158,814 269,831 199,821 -- ------------ ------------ ------------ ------------ ------------ Total additions .................. 87,033 523,912 816,006 1,202,767 86,155 Deductions - distributions ........... 7,325 343,832 234,611 3,836,816 46,539 Net interfund transfers .............. (47,098) (401,387) 341,380 4,321,992 (148,928) ------------ ------------ ------------ ------------ ------------ Net increase (decrease) .............. 32,610 (221,307) 922,775 1,687,943 (109,312) Assets transferred to another plan ... (167,043) (2,295,582) (2,519,905) (8,251,803) (173,185) Net assets available for benefits: Beginning of year .................. 604,321 5,507,309 4,787,468 19,196,152 572,551 ------------ ------------ ------------ ------------ ------------ End of year ........................ $ 469,888 $ 2,990,420 $ 3,190,338 $ 12,632,292 $ 290,054 ============ ============ ============ ============ ============

Fund Information (Continued) ----------------------------- Common Stock Funds ----------------------------- Halliburton/ Cash NL Tremont Fund Total ------------ ------------ ------------ ------------ Investment income: Net appreciation (depreciation) in the fair value of investments ... $ 672,669 $ (146,054) $ -- $ 2,143,148 Dividend income: NL Industries, Inc. ............ 13,803 -- -- 13,803 Halliburton Company ............ -- 1,239 -- 1,239 Dresser Industries ............. -- 6,057 -- 6,057 Tremont Corporation ............ -- 453 -- 453 Other .......................... -- -- -- 739,174 Interest income .................. -- -- (8,895) 994,051 ------------ ------------ ------------ ------------ Total investment income .......... 686,472 (138,305) (8,895) 3,897,925 ------------ ------------ ------------ ------------ Contributions: Participants ..................... 74,125 -- (44,594) 664,443 Employer ......................... 45,020 -- 1,370 599,899 ------------ ------------ ------------ ------------ Total contributions ............ 119,145 -- (43,224) 1,264,342 ------------ ------------ ------------ ------------ Total additions .................. 805,617 (138,305) (52,119) 5,162,267 Deductions - distributions ........... 35,384 5,434 15,554 4,812,063 Net interfund transfers .............. (1,373,683) (133,844) -- -- ------------ ------------ ------------ ------------ Net increase (decrease) .............. (603,450) (277,583) (67,673) 350,204 Assets transferred to another plan ... (409,376) -- -- (17,584,967) Net assets available for benefits: Beginning of year .................. 3,041,977 641,313 67,673 43,588,098 ------------ ------------ ------------ ------------ End of year ........................ $ 2,029,151 $ 363,730 $ -- $ 26,353,335 ============ ============ ============ ============ F-5

NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS WITH FUND INFORMATION (CONTINUED) Year ended December 31, 1999 Fund Information ------------------------------------------------------------ AIM MFS Emerging Templeton International AIM Value Growth Fund World Fund Equity Fund Fund ------------ ---------- ------------- --------- Additions: Investment income: Net appreciation (depreciation) in the fair value of investments ... $ 518,333 $ 118,136 $ 142,437 $ 288,492 Dividend income: NL Industries, Inc. .......... -- -- -- -- Halliburton Company .......... -- -- -- -- Tremont Corporation .......... -- -- -- -- Other ........................ 7,352 56,641 14,768 124,316 Interest income ................ -- -- -- -- ----------- ----------- ----------- ----------- Total investment income ........ 525,685 174,777 157,205 412,808 ----------- ----------- ----------- ----------- Contributions: Participants ................... 74,441 28,241 20,758 85,351 Employer ....................... 37,774 20,306 17,214 40,660 ----------- ----------- ----------- ----------- Total contributions .......... 112,215 48,547 37,972 126,011 ----------- ----------- ----------- ----------- Total additions ................ 637,900 223,324 195,177 538,819 Deductions - distributions ......... 81,362 50,707 23,543 98,892 Net interfund transfers ............ (267,567) (3,145) 20,048 470,320 ----------- ----------- ----------- ----------- Net increase (decrease) ............ 288,971 169,472 191,682 910,247 Net assets available for benefits: Beginning of year ................ 1,323,433 639,642 287,121 1,086,632 ----------- ----------- ----------- ----------- End of year ...................... $ 1,612,404 $ 809,114 $ 478,803 $ 1,996,879 =========== =========== =========== ===========

ML Global MFS Government ML Equity Allocation Securities Fund Index Trust Fund, Inc. --------------- ----------- ----------- Additions: Investment income: Net appreciation (depreciation) in the fair value of investments ... $ (24,919) $ 114,469 $ 24,805 Dividend income: NL Industries, Inc. .......... -- -- -- Halliburton Company .......... -- -- -- Tremont Corporation .......... -- -- -- Other ........................ 16,991 -- 40,600 Interest income ................ -- -- -- ----------- ----------- ----------- Total investment income ........ (7,928) 114,469 65,405 ----------- ----------- ----------- Contributions: Participants ................... 8,304 60,162 15,788 Employer ....................... 3,455 33,690 5,181 ----------- ----------- ----------- Total contributions .......... 11,759 93,852 20,969 ----------- ----------- ----------- Total additions ................ 3,831 208,321 86,374 Deductions - distributions ......... 29,000 85,815 72,139 Net interfund transfers ............ (19,420) 79,097 9,574 ----------- ----------- ----------- Net increase (decrease) ............ (44,589) 201,603 23,809 Net assets available for benefits: Beginning of year ................ 283,535 498,860 268,239 ----------- ----------- ----------- End of year ...................... $ 238,946 $ 700,463 $ 292,048 =========== =========== =========== F-6

NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN STATEMENTS OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS WITH FUND INFORMATION (CONTINUED) Year ended December 31, 1999 (Continued) Fund Information (Continued) -------------------------------------------------------------------------------- Mercury ML Federal ML Capital ML Basic ML Retirement Global Securities Fund, Value Preservation Holdings, Trust Inc. Fund Trust Inc. ------------ ------------ ------------ ------------ ------------ Additions: Investment income: Net appreciation (depreciation) in the fair value of investments ... $ (20,367) $ (183,315) $ 12,462 $ -- $ 31,467 Dividend income: NL Industries, Inc. ............ -- -- -- -- -- Halliburton Company ............ -- -- -- -- -- Tremont Corporation ............ -- -- -- -- -- Other .......................... 21,110 309,531 328,016 -- 99,114 Interest income .................. -- -- -- 699,089 -- ------------ ------------ ------------ ------------ ------------ Total investment income .......... 743 126,216 340,478 699,089 130,581 ------------ ------------ ------------ ------------ ------------ Contributions: Participants ..................... 26,749 59,046 135,093 78,060 -- Employer ......................... 10,816 20,089 61,242 42,939 -- ------------ ------------ ------------ ------------ ------------ Total contributions ............ 37,565 79,135 196,335 120,999 -- ------------ ------------ ------------ ------------ ------------ Total additions .................. 38,308 205,351 536,813 820,088 130,581 Deductions - distributions ........... 216,318 228,954 190,792 3,024,555 11,475 Net interfund transfers .............. (57,983) (264,869) (388,612) 579,246 (3,777) ------------ ------------ ------------ ------------ ------------ Net increase (decrease) .............. (235,993) (288,472) (42,591) (1,625,221) 115,329 Net assets available for benefits: Beginning of year .................. 469,888 2,990,420 3,190,338 12,632,292 290,054 ------------ ------------ ------------ ------------ ------------ End of year ........................ $ 233,895 $ 2,701,948 $ 3,147,747 $ 11,007,071 $ 405,383 ============ ============ ============ ============ ============

Fund Information (Continued) ----------------------------- Common Stock Funds ----------------------------- Halliburton/ Cash NL Tremont Fund Total ------------ ------------ ------------ ------------ Additions: Investment income: Net appreciation (depreciation) in the fair value of investments ... $ 132,645 $ 75,437 $ -- $ 1,230,082 Dividend income: NL Industries, Inc. ............ 20,054 -- -- 20,054 Halliburton Company ............ -- 4,027 -- 4,027 Tremont Corporation ............ -- 594 -- 594 Other .......................... -- -- -- 1,018,439 Interest income .................. -- -- -- 699,089 ------------ ------------ ------------ ------------ Total investment income .......... 152,699 80,058 -- 2,972,285 ------------ ------------ ------------ ------------ Contributions: Participants ..................... 50,052 -- 35,374 677,419 Employer ......................... 14,092 -- -- 307,458 ------------ ------------ ------------ ------------ Total contributions ............ 64,144 -- 35,374 984,877 ------------ ------------ ------------ ------------ Total additions .................. 216,843 80,058 35,374 3,957,162 Deductions - distributions ........... 90,570 2,980 (1,053) 4,206,049 Net interfund transfers .............. (38,612) (114,300) -- -- ------------ ------------ ------------ ------------ Net increase (decrease) .............. 87,661 (37,222) 36,427 (248,887) Net assets available for benefits: Beginning of year .................. 2,029,151 363,730 -- 26,353,335 ------------ ------------ ------------ ------------ End of year ........................ $ 2,116,812 $ 326,508 $ 36,427 $ 26,104,448 ============ ============ ============ ============ See accompanying notes to financial statements. F-7

NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN NOTES TO FINANCIAL STATEMENTS Note 1 - Summary of significant accounting policies: The financial statements of the NL Industries, Inc. Retirement Savings Plan (the "Plan") have been prepared in accordance with accounting principles generally accepted in the United States. The following is a summary of the significant accounting policies followed by the Plan. Investments Investments are recorded at fair value based upon the quoted market price reported on the last trading day of the period for those securities listed on a national securities exchange. Listed securities for which no sale was reported on that date are valued at the mean between the last reported bid and ask prices. Short-term investments are stated at fair value. Purchases and sales of investments are reflected on a trade-date basis. Gains or losses on sales of securities are based on average cost. The Plan presents in the statements of changes in net assets available for plan benefits the net appreciation (depreciation) in the fair value of its investments which consists of the realized gains or losses and the unrealized appreciation (depreciation) on those investments. Contributions Contributions from employees are recorded in the period the employer makes payroll deductions from Plan participants. Employer contributions, if any, are accrued at the end of each year and are received in the subsequent year. Investment income Income from investments is recorded as earned on an accrual basis. Dividend income is recorded at the ex-dividend date. Termination of Plan Although it has not expressed any intent to do so, NL Industries, Inc. has the right under the Plan to discontinue contributions and to terminate the Plan at any time subject to penalties set forth in the Employee Retirement Income Security Act of 1974 ("ERISA"). In the event of such a discontinuance or termination of the Plan, the net assets of the Plan would be allocated to the Plan participants as prescribed by the Plan document, ERISA, and the Internal Revenue Code. Management's Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the reported amounts of net assets available for benefits at the date of the financial statements, the changes in net assets available for benefits during the reporting period and, when applicable, the disclosures of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates. Note 2 - Plan description: The Plan's principal objective is to provide eligible employees of NL Industries, Inc. and its U.S. subsidiaries (the "Company") with a convenient way to save on a regular and long-term basis. The majority of the Company's U.S. employees are eligible to voluntarily participate in the Plan after six months of employment. At December 31, 1999, there were 74 active participants (participants currently employed by the Company) and 504 total participants. Active participants may make basic contributions of between 0% and 8% of their eligible compensation. Basic contributions may consist of a combination of F-8

pre-tax and after- tax earnings. Generally, pre-tax contributions are excluded from the employee's taxable income until they are distributed. Eligible employees that have elected to make the maximum basic contribution of 8% may also make a supplemental pre-tax or after-tax contribution of between 1% and 4% of their eligible compensation. In accordance with the Tax Reform Act of 1986, participants are limited in the amount of salary reduction contributions which they may make to the Plan under Section 402(g) of the Internal Revenue Code ($10,000 annual maximum for 1999). Highly compensated participants may be required to adjust the amount of their contributions in order to permit the Plan to satisfy the nondiscrimination requirements of Sections 401(k) and 401(m) of the Internal Revenue Code. Employer contributions include funds that (i) match a portion of participants' contributions and (ii) represent an annual contribution of 3% of employees eligible earnings. The Company's level of matching contributions is determined annually and is based upon the attainment of certain operating income target levels approved by the Management, Development and Compensation Committee of the Board of Directors of the Company (the "MD&C Committee"). The Company match applies only to participants' basic contributions. The level of match approved by the MD&C Committee for 1998 and 1999 was 75% and 50%, respectively. Employees who are eligible to participate in the Plan receive an annual contribution to their investment account of 3% of their eligible compensation, subject to IRS limitations on eligible compensation, which for 1999 was $160,000. The Company makes this annual contribution for each eligible employee regardless of whether the employee elects to otherwise participate in the Plan. Beginning in 2000, the Company intends to increase the employer contribution from 3% to 4%. A participant with less than three years of service is 0% vested in employer contributions, 50% vested following three years of service, 75% vested following four years of service and fully vested in all employer contributions following five years of service. Employer contributions are fully vested upon death, retirement, or disability, as provided in the Plan. Forfeitures of employer contributions may occur if a participant terminates employment prior to the full vesting period or if a participant or beneficiary, to whom a distribution is payable, cannot be located within five years of the date on which such distribution became payable. Forfeitures were $18,015 in 1998 and $20,067 in 1999. Amounts forfeited are used in the following order: (i) to restore the accounts of reemployed participants, (ii) to restore the accounts of participants or beneficiaries who apply for forfeited benefits, and (iii) to reduce employer contributions. The balance in the forfeiture account at December 31, 1999 was $236,139. Substantially all of this balance is expected to be used to reduce future employer contributions. The Plan was amended effective January 1, 2000 to provide participants with the opportunity to borrow cash from their vested savings balance. Participants will be able to borrow from their fund accounts a minimum of $1,000 up to a maximum that is generally equal to the lesser of $50,000 or 50 percent of their account balance, whichever is less. The loans will be collateralized by the balance in the participant's account and bear interest at rates which are commensurate with local prevailing rates. Principal and interest will be repaid ratably through monthly payroll deductions. The specialty chemical business of Rheox, Inc., a wholly owned subsidiary of the Company, was sold to Elementis plc in January 1998 and $18 million of the Plan's assets were distributed to Elementis America Inc. Rheox Inc. Retirement Savings Plan, a retirement plan administered by Elementis plc. Merrill Lynch Trust Company ("Merrill Lynch" or "ML") serves as trustee for the Plan. Employees may elect to have their own contributions invested in one or more funds, whose investment objectives are as follows: F-9

Number of participants at December 31, --------------- 1998 1999 ---- ---- MFS Emerging Growth Fund - Class A Shares - managed with the objective of 62 65 providing long-term growth of capital by investing primarily in common stocks of companies that are early in their life cycles or are major enterprises whose rates of earnings growth are expected to accelerate. Templeton World Fund - Class A Shares - managed with the objective of seeking 44 47 long-term capital growth by investing in securities of companies or governments located throughout the world. The fund's portfolio is invested in securities of both U.S. and foreign issuers. AIM International Equity Fund - Class A Shares - managed with the objective of 37 40 seeking long-term return of capital by investing in a diversified portfolio of international equity securities. AIM Value Fund - Class A Shares - managed with the objective of achieving 58 72 long-term growth of capital by investing primarily in equity securities of large companies with strong earnings prospects that are undervalued relative to the equity market as a whole. MFS Government Securities Fund - Class A Shares - managed with the objective of 27 21 providing current income and preservation of principal by investing in Government Securities and by investing in obligations that are fully collateralized or otherwise fully secured by Government Securities. Merrill Lynch Equity Index Trust - managed with the objective of approximating 46 55 the total return of the Standard & Poor's 500 Composite Stock Index. This index is a means to measure the performance of a broad base of large U.S. corporations. Merrill Lynch Global Allocation Fund, Inc. - Class A Shares - managed with the 38 35 objective of seeking a high total investment return, consistent with the prudent risk, through a fully managed investment policy utilizing United States and foreign equity, debt and money market securities the combination of which will be varied from time to time both with respect to types of securities and markets in response to changing market and economic trends. Merrill Lynch Federal Securities Trust - Class A Shares - managed with the 72 40 objective of seeking a high current return through investments in U.S. government and government agency securities. Merrill Lynch Capital Fund, Inc. - Class A Shares - managed with the objective 98 94 of seeking the highest total investment return through a fully managed investment policy utilizing equity, debt (including money market) and convertible securities. Merrill Lynch Basic Value Fund, Inc. - Class A Shares - managed with the 94 92 objective of seeking capital appreciation and, secondarily, income by investing in securities, primarily equities, that fund management believes to be undervalued. Merrill Lynch Retirement Preservation Trust - managed with the objective of 300 174 providing preservation of capital, liquidity and current income at levels typically higher than those provided by money market funds. The trust invests primarily in a broadly diversified portfolio of Guaranteed Investment Contracts and in high-quality money market securities. NL Stock Fund - invested in NL common stock. 377 354 F-10

In addition to the funds listed above, the Halliburton/Tremont Stock Fund holds investments in Halliburton for 44 participants and Tremont Corporation common stock for 32 participants. Investments in the Mercury Global Holdings Fund (formerly the Merrill Lynch Global Holdings Fund), with 17 participants, were frozen in 1996. Contributions or transfers into the Halliburton/Tremont Stock Fund and the Mercury Global Holdings Fund are no longer allowed. Prior to the investment in securities of a type consistent with the objectives of any fund, cash may be temporarily invested in securities with maturities of less than one year issued or guaranteed by the U.S. government or any agency or instrumentality thereof or deposited in a bank savings account. Interfund transfers may be made daily, except that only one transfer per participant per quarter may affect amounts in the NL Stock Fund. Only one transfer is permitted out of the Halliburton/Tremont Stock Fund which must be a transfer of the total value of the participant's account in that fund. Distributions to employees may occur during active service or upon termination and under prescribed circumstances. Distributions may be in the form of lump sums, installments, annuities, or combinations thereof, or distributions of employer securities. The Company bears the responsibility of all administrative expenses of the Plan. Note 3 - Related party transactions: The NL Stock Fund and the Halliburton/Tremont Stock Fund invest in the common stock of NL and Tremont, both of which entities are considered related parties. The activity of these securities for the years ended December 31, 1998 and 1999 was as follows: Sales and distributions, Realized Purchases at cost gain (loss) ----------- -------------- ----------- Year ended December 31, 1998: NL common stock ........... $ 302,532 $1,155,944 $ 758,178 Tremont common stock ...... 453 3,085 18,782 Year ended December 31, 1999: NL common stock ........... $ 158,787 $ 289,856 $ (117,013) Tremont common stock ...... 594 541 544 Note 4 - Tax status: The Plan, as amended, is designed to constitute a qualified trust under Sections 401(a) and 401(k) of the Internal Revenue Code of 1986, as amended (the "Code"); as such the Plan is exempt from federal income tax, and amounts contributed by the Company will not be taxed to the participant until the participant receives a distribution from the Plan. The Plan has received a favorable determination as of March 1998, indicating it is a "Qualified Plan" under the requirements of Sections 401(a) and 401(k) of the Code and is qualified for favorable tax treatment. The Company intends to file an application with the Internal Revenue Service for a determination of the qualified status of the Plan under Section 401(a) of the code for all amendments made to the Plan since the last determination letter. F-11

Note 5 - Investments: The historical cost and fair value of each of the investments and the employer contributions receivable balances at December 31, 1998 and 1999 were as follows: December 31, ----------------------------------------------------------------------------------------- 1998 1999 -------------------------------------------- ------------------------------------------ Employer Employer Historical contributions Historical contributions Fund description cost Fair value receivable cost Fair value receivable - ---------------------------------------- ---------- ---------- ------------- ---------- ---------- ------------- NL Stock Fund .......................... $ 1,915,419 $ 1,984,132 $ 45,019 $ 1,784,350 $ 2,102,721 $ 14,091 Halliburton/Tremont Stock Fund: Halliburton common stock ............. 111,251 292,779 -- 83,352 294,938 -- Tremont common stock ................. 18,061 70,951 -- 18,113 31,570 -- ----------- ----------- ----------- ----------- ----------- ----------- Total common stock ............... 2,044,731 2,347,862 45,019 1,885,815 2,429,229 14,091 ----------- ----------- ----------- ----------- ----------- ----------- MFS Emerging Growth Fund - Class A Shares ........................ 970,670 1,278,402 45,031 839,743 1,574,630 37,774 Templeton World Fund - Class A Shares ........................ 651,335 615,177 24,465 710,937 788,808 20,306 AIM International Equity Fund - Class A Shares ........................ 238,380 267,444 19,677 295,501 461,589 17,214 AIM Value Fund - Class A Shares ........ 856,310 1,027,619 59,013 1,530,196 1,956,219 40,660 MFS Government Securities Fund - Class A Shares ........................ 259,186 271,136 12,399 243,810 235,490 3,456 Merrill Lynch Equity Index Trust ....... 321,945 462,080 36,780 439,237 666,773 33,690 Merrill Lynch Global Allocation Fund, Inc. - Class A Shares ................. 287,551 249,476 18,763 294,057 286,867 5,181 Merrill Lynch Federal Securities Trust - Class A Shares ........................ 435,316 440,463 29,425 230,397 223,078 10,817 Merrill Lynch Capital Fund, Inc. - Class A Shares ........................ 2,490,537 2,918,680 71,740 2,511,013 2,681,860 20,088 Merrill Lynch Basic Value Fund, Inc. - Class A Shares ........................ 2,396,955 3,053,911 136,427 2,605,534 3,086,505 61,242 Merrill Lynch Retirement Preservation Trust ................................. 12,532,499 12,532,499 99,793 10,964,132 10,964,132 42,939 Mercury Global Holdings, Inc. - Class I Shares ........................ 274,766 290,054 -- 360,422 405,383 -- ----------- ----------- ----------- ----------- ----------- ----------- Total other securities ........... 21,715,450 23,406,941 553,513 21,024,979 23,331,334 293,367 ----------- ----------- ----------- ----------- ----------- ----------- $23,760,181 $25,754,803 $ 598,532 $22,910,794 $25,760,563 $ 307,458 =========== =========== =========== =========== =========== =========== Investments whose fair value exceeds five percent of net assets available for benefits were the NL Stock Fund, Merrill Lynch Capital Fund, Merrill Lynch Basic Value Fund, and Merrill Lynch Retirement Preservation Trust Fund at December 31, 1998 and 1999 and the MFS Emerging Growth Fund and the AIM Value Fund at December 31, 1999. F-12

Cash at December 31, 1999 of $36,427 represents rollover contributions from participants which have not yet been allocated to individual funds. At June 8, 2000, the market value of the shares of NL, Halliburton and Tremont stock held at December 31, 1999 was $2,399,450, $341,659 and $37,094, respectively. The Plan's assets are invested principally in common stock of NL, Halliburton and Tremont, and with investment funds managed by (i) Merrill Lynch, ii) Massachusetts Financial Services ("MFS"), iii) AIM Advisors, Inc., and iv) Templeton Global Advisors Limited. At December 31, 1999, 71% of the Plan's investments were managed by Merrill Lynch. F-13

SUPPLEMENTAL SCHEDULES

NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN SCHEDULE OF ASSETS HELD FOR INVESTMENT PURPOSES AT END OF YEAR December 31, 1999 Employer Identification No. 13-5267260 Plan No. 003 Cost Fair value ----------- ----------- MFS Emerging Growth Fund - Class A shares ...................... $ 839,743 $ 1,574,630 Templeton World Fund - Class A shares .......................... 710,937 788,808 AIM International Equity Fund - Class A shares ................. 295,501 461,589 AIM Value Fund - Class A shares ................................ 1,530,196 1,956,219 MFS Government Securities Fund - Class A shares ................ 243,810 235,490 * Merrill Lynch Equity Index Trust ............................... 439,237 666,773 * Merrill Lynch Global Allocation Fund, Inc.- Class A shares ..... 294,057 286,867 * Merrill Lynch Federal Securities Trust - Class A shares ........ 230,397 223,078 * Merrill Lynch Capital Fund, Inc. - Class A shares .............. 2,511,013 2,681,860 * Merrill Lynch Basic Value Fund, Inc. - Class A shares .......... 2,605,534 3,086,505 * Merrill Lynch Retirement Preservation Trust .................... 10,964,132 10,964,132 * Mercury Global Holdings, Inc. - Class I shares (formerly Merrill Lynch Global Holdings) ....................................... 360,422 405,383 * NL Stock Fund - common stock ................................... 1,784,350 2,102,721 Halliburton/Tremont Stock Fund - common stock: Halliburton Company ......................................... 83,352 294,938 * Tremont Corporation ......................................... 18,113 31,570 ----------- ----------- $22,910,794 $25,760,563 =========== =========== Note: Cost is determined based on historical cost. Gains and losses on sales of investments are calculated based on average cost. * Investment in a "Party-in-interest" entity, as defined by ERISA. F-14

NL INDUSTRIES, INC. RETIREMENT SAVINGS PLAN SCHEDULE OF REPORTABLE TRANSACTIONS Year ended December 31, 1999 Employer Identification No. 13-5267260 Plan No. 003 Fair value of asset on Number of Purchase Selling Cost of transaction Description of Asset Transactions price price asset date Net gain - -------------------- ------------ ---------- -------- ---------- ----------- ----------- Merrill Lynch Retirement Preservation Trust: Purchases ................................ 97 $2,030,303 $ -- $2,030,303 $2,030,303 $ -- Sales .................................... 58 -- 3,598,571 3,598,571 3,598,571 -- Merrill Lynch Basic Value Fund Class A: Purchases ................................ 44 828,671 -- 828,671 828,671 -- Sales .................................... 33 -- 789,896 601,449 789,896 188,447 F-15

EXHIBIT I CONSENT OF INDEPENDENT ACCOUNTANTS We hereby consent to the incorporation by reference in the: (i) Registration Statement No. 33-29287 on Form S-8 and related Prospectus with respect to the 1989 Long Term Performance Incentive Plan of NL Industries, Inc.; and (ii) Registration Statement No. 33-25913 on Form S-8 and related Prospectus with respect to the NL Industries, Inc. Retirement Savings Plan; and (iii) Registration Statement No. 33-48145 on Form S-8 and related Prospectus with respect to the NL Industries, Inc. 1992 Non-Employee Directors Stock Option Plan; and (iv) Registration Statement No. 333-65817 on Form S-8 and related Prospectus with respect to the NL Industries, Inc. 1998 Long-Term Incentive Plan. of our report dated June 8, 2000 relating to the financial statements of the NL Industries, Inc. Retirement Savings Plan which appears in this Form 11-K. PricewaterhouseCoopers LLP Houston, Texas June 27, 2000