KRONOS WORLDWIDE INC — Director's Dealing 2010

May 14, 2010

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: KRONOS WORLDWIDE INC (KRO)
CIK: 0001257640
Period of Report: 2010-05-13

Reporting Person: SIMMONS HAROLD C (Director, Chairman of the Board, 10% Owner)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2010-05-13	Common Stock $0.01 par value	A	1000	—	Acquired	237509	Direct

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock $0.01 par value	28995021	Indirect
Common Stock $0.01 par value	17609635	Indirect
Common Stock $0.01 par value	79567	Indirect
Common Stock $0.01 par value	54856	Indirect
Common Stock $0.01 par value	2686	Indirect

Footnotes

F1: Shares issued for no cash consideration to nonemployee directors under the Kronos Worldwide, Inc. 2003 Long-Term Incentive Plan.

F2: Directly held by Valhi, Inc. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationship to the reporting person.

F3: 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 reporting person.

F4: Directly held by TIMET Finance Management Company. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationship to the reporting person.

F5: Directly held by the reporting person's spouse. The reporting person disclaims beneficial ownership of, and a pecuniary interest in, any shares of the issuer's common stock that his spouse holds.

F6: Directly held by Contran Corporation. See the Additional Information filed as Exhibit 99 to this statement for a description of the relationship to the reporting person.