-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 R6z6OwbO72odF2LVA2+2EAPB0XOnk1ppVG+Mqv/U4t1ib837Ci8WKOllHRx9a5tF
 uNXSsRiBTlm7w5re3x97/Q==

<SEC-DOCUMENT>0001257640-03-000049.txt : 20031219
<SEC-HEADER>0001257640-03-000049.hdr.sgml : 20031219
<ACCEPTANCE-DATETIME>20031219153302
ACCESSION NUMBER:		0001257640-03-000049
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031218
FILED AS OF DATE:		20031219

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			KRONOS WORLDWIDE INC
		CENTRAL INDEX KEY:			0001257640
		STANDARD INDUSTRIAL CLASSIFICATION:	INDUSTRIAL INORGANIC CHEMICALS [2810]
		IRS NUMBER:				760294959

	BUSINESS ADDRESS:	
		STREET 1:		5430 LBJ FREEWAY
		STREET 2:		SUITE 1700
		CITY:			DALLAS
		STATE:			TX
		ZIP:			75240
		BUSINESS PHONE:		9722331700

	MAIL ADDRESS:	
		STREET 1:		5430 LBJ FREEWAY
		STREET 2:		SUITE 1700
		CITY:			DALLAS
		STATE:			TX
		ZIP:			75240

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	KRONOS INC
		DATE OF NAME CHANGE:	20030730

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			VALHI INC /DE/
		CENTRAL INDEX KEY:			0000059255
		STANDARD INDUSTRIAL CLASSIFICATION:	SUGAR & CONFECTIONERY PRODUCTS [2060]
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-31763
		FILM NUMBER:		031065129

	BUSINESS ADDRESS:	
		STREET 1:		5430 LBJ FRWY
		STREET 2:		STE 1700
		CITY:			DALLAS
		STATE:			TX
		ZIP:			75240
		BUSINESS PHONE:		9722331700

	MAIL ADDRESS:	
		STREET 1:		THREE LINCOLN CENTER
		STREET 2:		5430 LBJ FREEWAY SUITE 1700
		CITY:			DALLAS
		STATE:			TX
		ZIP:			75240

	FORMER NAME:	
		FORMER CONFORMED NAME:	LLC CORP
		DATE OF NAME CHANGE:	19870329

	FORMER NAME:	
		FORMER CONFORMED NAME:	LIBERTY LOAN CORP
		DATE OF NAME CHANGE:	19800414
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>

<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2003-12-18</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001257640</issuerCik>
        <issuerName>KRONOS WORLDWIDE INC</issuerName>
        <issuerTradingSymbol>kro</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000059255</rptOwnerCik>
            <rptOwnerName>VALHI INC /DE/</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>THREE LINCOLN CENTER</rptOwnerStreet1>
            <rptOwnerStreet2>5430 LBJ FREEWAY SUITE 1700</rptOwnerStreet2>
            <rptOwnerCity>DALLAS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75240</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>

        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock $0.01 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2003-12-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18.25</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15106395</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock $0.01 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2003-12-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>200</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18.2</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15106595</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock $0.01 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2003-12-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>100</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>17.95</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15106695</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock $0.01 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2003-12-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15107195</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock $0.01 par value</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25061007</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by NL</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>

        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock $0.01 par value</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5107770</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Tremont</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>

    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Directly held by NL Industries, Inc. See the Additional Information filed as an exhibit to this statement for a description of the relationship.</footnote>
        <footnote id="F2">Directly held by Tremont LLC.  See the Additional information filed as an exhibit to this statement for a description of the relationship.</footnote>
    </footnotes>


    <ownerSignature>
        <signatureName>A. Andrew R. Louis, Secretary, for Valhi, Inc.</signatureName>
        <signatureDate>2003-12-19</signatureDate>
    </ownerSignature>

</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----