Sec Form 4 Filing - SIMMONS HAROLD C @ KRONOS WORLDWIDE INC - 2013-03-13

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person SIMMONS HAROLD C 2. Issuer Name and Ticker or Trading Symbol KRONOS WORLDWIDE INC [ KRO] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chairman of the Board (Last) (First) (Middle) 5430 LBJ FREEWAY, SUITE 1700 3. Date of Earliest Transaction (MM/DD/YY) 03/13/2013 (Street) DALLAS, TX75240 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock $0.01 par value 03/13/2013 J( 1 ) 100,000 A $ 16.7522 ( 1 ) 105,372 ( 2 ) I By Contran ( 2 ) Common Stock $0.01 par value 787,876 I by Spouse ( 3 ) Common Stock $0.01 par value 57,990,042 ( 4 ) I by Valhi ( 4 ) Common Stock $0.01 par value 35,219,270 ( 5 ) I by NL ( 5 ) Common Stock $0.01 par value 782,840 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other SIMMONS HAROLD C 5430 LBJ FREEWAY, SUITE 1700 DALLAS, TX75240 X X Chairman of the Board CONTRAN CORP 5430 LBJ FREEWAY, SUITE 1700 DALLAS, TX75240 X Signatures A. Andrew R. Louis. Secretary, for Contran Corporation 03/13/2013 Signature of Reporting Person Date A. Andrew R. Louis. Attorney-in-fact, for Harold C. Simmons 03/13/2013 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Open market purchase by Contran Corporation. The price reported in Column 4 is a weighted average price. These acquisitions involved 37 purchases at prices ranging from $16.39 to $16.81 per share. The reporting person undertakes to provide to the issuer, any security holder of the issuer or the U.S. Security and Exchange Commission, upon request, the full information regarding these pruchases. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationship among the reporting persons. ( 2 )Directly held by Contran Corporation. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationship of an additional person who may be deemed to beneficially own these shares. ( 3 )Directly held by the reporting person's spouse. The reporting person disclaims beneficial ownership of any shares of the issuer's common stock that his spouse holds. ( 4 )Directly held by Valhi, Inc. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationships to the persons joining in this filing. ( 5 )Directly held by NL Industries, Inc. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationship to the persons joining in this filing.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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