PROMISSORY NOTE

$200,000,000.00                  October __, 2003                 Dallas, Texas

     FOR VALUE RECEIVED,  the undersigned,  Kronos  Worldwide,  Inc., a Delaware
corporation,  unconditionally  promises  to pay to the  order of NL  Industries,
Inc., a New Jersey corporation, in lawful money of the United States of America,
the principal sum of TWO HUNDRED MILLION and NO/100ths DOLLARS ($200,000,000.00)
together  with  interest  from the  date of this  Note on the  unpaid  principal
balance from time to time pursuant to the terms of this Note. This Note shall be
unsecured  and will bear  interest  on the  terms set forth in  Section 4 below.
Capitalized  terms not otherwise  defined shall have the meanings  given to such
terms in Section 14 of this Note.

     Section 1.Place of Payment. All payments will be made at Payee's address at
Three Lincoln Centre, 5430 LBJ Freeway, Suite 1700, Dallas, Texas 75240-2697, or
such other place as the Payee may from time to time  designate  in  writing,  in
immediately available funds, without setoff or counterclaim.

     Section 2. Payment.  The principal  balance of this Note and any unpaid and
accrued  interest  thereon shall be due and payable on the Maturity Date or upon
acceleration  as provided  herein.  Prior to the Maturity Date or  acceleration,
unpaid and accrued  interest on the outstanding  principal  balance of this Note
shall be due and  payable  quarterly  on March  31,  June 30,  September  30 and
December 31 of each year;  provided,  however,  that such day is a business day,
and if such day is not a business day, the quarterly  interest  payment shall be
due the next successive business day.

     Section 3.  Prepayment.  This Note may be prepaid in part or in full at any
time without penalty; provided,  however,  prepayments shall be first applied to
accrued and unpaid interest and then to principal.

     Section 4. Interest. The unpaid balance of this Note (exclusive of any past
due  principal)  shall bear interest at an annual rate of nine percent (9%). Ten
business days after the Maturity Date or  acceleration as provided in this Note,
all past due  principal  and past due  interest  owed  under this Note will bear
interest  at an annual rate of twelve  percent  (12%).  Accrued  interest on the
unpaid principal of this Note shall be computed on the basis of a 365 or 366-day
year, as the case may be, for actual days elapsed. In no event,  however,  shall
such  computation  result in an amount of accrued  interest  that  would  exceed
accrued interest on the unpaid  principal  balance during the same period at the
Maximum Rate.  Notwithstanding  anything to the contrary, this Note is expressly
limited so that in no contingency or event  whatsoever  shall the amount paid or
agreed  to be  paid  to  the  Payee  exceed  the  Maximum  Rate.  If,  from  any
circumstances  whatsoever,  the Payee  shall ever  receive as interest an amount
that would exceed the Maximum Rate, such amount received that would be in excess
of the Maximum Rate shall be applied to the  reduction  of the unpaid  principal
balance and not to the payment of interest,  and if the principal amount of this
Note is paid in full, any remaining  excess shall be paid to Maker,  and in such
event, the Payee shall not be subject to any penalties  provided by any laws for
contracting for, charging,  taking, reserving or receiving interest in excess of
the highest lawful rate permissible under applicable law.

     Section 5. Remedy.  Upon the occurrence and during the  continuation  of an
Event of Default,  Payee may, at its option, declare the entire unpaid principal
of this Note,  and all accrued  interest and other  amounts  payable  hereunder,
immediately due and payable without presentment, demand, protest or other notice
of any  kind,  all of which  are  expressly  waived  by  Maker,  and  upon  such
declaration, such amounts shall become and shall be immediately due and payable.
The Payee shall have all of the rights and remedies  provided in the  applicable
Uniform Commercial Code or in this Note or any other agreement between Maker and
in favor of the Payee,  as well as those  rights and  remedies  provided  by any
other  applicable law, rule or regulation.  All rights and remedies of the Payee
are cumulative and may be exercised singly or concurrently.  The exercise of any
right or remedy  will not be a waiver of any other  right or remedy.  Failure to
exercise any right or remedy upon the  occurrence  of an Event of Default  shall
not  constitute a waiver of the right to exercise  such right or remedy upon the
occurrence of a subsequent Event of Default.

     Section  6.  Right of  Offset.  The  Payee  shall  have the right of offset
against  amounts  that may be due by the  Payee  now or in the  future  to Maker
against amounts due under this Note.

     Section 7.  Record of  Outstanding  Principal.  The date and amount of each
repayment of principal outstanding under this Note shall be recorded by Payee in
its records.  The aggregate unpaid principal  balance so recorded by Payee shall
be the best evidence of the principal  balance owing and unpaid under this Note;


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so  recording  any  such  balance  shall  not  limit  or  otherwise  affect  the
obligations of Maker under this Note to repay the principal balance  outstanding
and all accrued or accruing interest.

     Section 8. Waiver. Maker and each surety,  endorser,  guarantor,  and other
party now or  subsequently  liable for  payment of this  Note,  severally  waive
demand, presentment for payment, notice of dishonor, protest, notice of protest,
diligence in  collecting or bringing suit against any party liable on this Note,
and further agree to any and all extensions,  renewals,  modifications,  partial
payments,  substitutions of evidence of indebtedness,  and the taking or release
of any collateral with or without notice before or after demand by the Payee for
payment under this Note.

     Section 9. Costs and  Attorneys'  Fees. In the event the Payee incurs costs
in collecting on this Note, this Note is placed in the hands of any attorney for
collection,  suit is filed on this Note or if proceedings are had in bankruptcy,
receivership,  reorganization,  or other legal or judicial  proceedings  for the
collection, Maker and any guarantor jointly and severally agree to pay on demand
to the Payee all expenses and costs of  collection,  including,  but not limited
to,  attorneys' fees incurred in connection with any such  collection,  suit, or
proceeding, in addition to the principal and interest then due.

     Section 10. Time of Essence.  Time is of the essence with respect to all of
Maker's obligations and agreements under this Note.

     Section  11.  Jurisdiction  and Venue.  This Note shall be  governed by and
construed in accordance  with the domestic  laws of the state of Texas,  without
giving effect to any choice of law or conflict of law provision or rule (whether
of  the  state  of  Texas  or any  other  jurisdiction)  that  would  cause  the
application of the laws of any jurisdiction other than the state of Texas. Maker
consents to jurisdiction in the courts located in Dallas, Texas.

     Section  12.  Notice.  Any notice or demand  required by this Note shall be
deemed to have been given and  received on the earlier of (i) when the notice or
demand is actually  received by the  recipient or (ii) 72 hours after the notice
is deposited in the United States mail,  certified or  registered,  with postage
prepaid, and addressed to the recipient. The address for giving notice or demand
under  this Note (i) to the Payee  shall be the place of  payment  specified  in
Section 1 or such other  place as the Payee may  specify in writing to the Maker
and (ii) to the Maker shall be the address  below the Maker's  signature or such
other place as the Maker may specify in writing to the Payee.

     Section 13.  Successors  and Assigns.  All of the  covenants,  obligations,
promises  and  agreements  contained in this Note made by Maker shall be binding
upon its successors and assigns;  notwithstanding the foregoing, Maker shall not
assign this Note or its  performance  under this Note without the prior  written
consent of the Payee.

     Section 14.  Definitions.  For purposes of this Note,  the following  terms
shall have the following meanings:

          (a) "Event of  Default"  shall mean the  failure by Maker to make when
     due a punctual  payment of  principal  of, or interest on, this Note within
     thirty (30) days  following the date such amount becomes due and payable in
     accordance with the terms of this Note.

          (b) "Maker" shall mean Kronos Worldwide, Inc., a Delaware corporation.

          (c) "Maturity Date" shall mean December 31, 2010.

          (d)  "Maximum  Rate"  shall mean the highest  lawful rate  permissible
     under applicable law for the use, forbearance or detention of money.

          (e) "Note" shall mean this Promissory Note.

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          (f) "Payee" shall mean NL Industries,  Inc., a New Jersey corporation,
     or subsequent holder of this Note.

                             MAKER:

                             KRONOS WORLDWIDE, INC.





                             Robert D. Graham, Vice President

                             Address:     Three Lincoln Centre
                                          5430 LBJ Freeway, Suite 1700
                                          Dallas, Texas   75240-2697
























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