-----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,
 JNHYAc6LdD7XPNpQRNJ3sYCkE7hn/ENOM3VVqE9Js2eLcIspZqOs404hiyQdbamV
 2TT0wPY6po6MF2tH3OxdOw==

<SEC-DOCUMENT>0000906280-03-000473.txt : 20031201
<SEC-HEADER>0000906280-03-000473.hdr.sgml : 20031201
<ACCEPTANCE-DATETIME>20031201121848
ACCESSION NUMBER:		0000906280-03-000473
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031126
FILED AS OF DATE:		20031201

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ADKERSON RICHARD C
		CENTRAL INDEX KEY:			0001200685

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-07791
		FILM NUMBER:		031029335

	BUSINESS ADDRESS:	
		STREET 1:		1615 POYDRAS STREET
		CITY:			NEW ORLEANS
		STATE:			LA
		ZIP:			70112
		BUSINESS PHONE:		5045824000

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MCMORAN EXPLORATION CO /DE/
		CENTRAL INDEX KEY:			0000064279
		STANDARD INDUSTRIAL CLASSIFICATION:	CRUDE PETROLEUM & NATURAL GAS [1311]
		IRS NUMBER:				721424200
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1615 POYDRAS ST
		CITY:			NEW ORLEANS
		STATE:			LA
		ZIP:			70112
		BUSINESS PHONE:		5045824000

	MAIL ADDRESS:	
		STREET 1:		1615 POYDRAS ST
		CITY:			NEW ORLEANS
		STATE:			LA
		ZIP:			70112

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MCMORAN OIL & GAS CO
		DATE OF NAME CHANGE:	19970707

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MCMORAN EXPLORATION CO
		DATE OF NAME CHANGE:	19790223

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	HORN SILVER MINES CO
		DATE OF NAME CHANGE:	19720620
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>f4100092031201_121757593.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-11-26</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000064279</issuerCik>
        <issuerName>MCMORAN EXPLORATION CO /DE/</issuerName>
        <issuerTradingSymbol>MMR</issuerTradingSymbol>
</issuer>
<reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001200685</rptOwnerCik>
            <rptOwnerName>ADKERSON RICHARD C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1615 POYDRAS STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW ORLEANS</rptOwnerCity>
            <rptOwnerState>LA</rptOwnerState>
            <rptOwnerZipCode>70112</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector>
<isOfficer>1</isOfficer>
<isTenPercentOwner>0</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle>Co-Chair of Board, Pres &amp; CEO</officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeTable>
<nonDerivativeTransaction>
<securityTitle>
<value>Common Stock</value>
</securityTitle>
<transactionDate>
<value>2003-11-26</value>
</transactionDate>
<transactionCoding>
<transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionTimeliness>
<value></value>
</transactionTimeliness>
<transactionAmounts>
<transactionShares>
<value>2254</value>
</transactionShares>
<transactionPricePerShare>
<value>16.4725</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode>
<value>A</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>97897</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value></value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeTransaction>
<nonDerivativeHolding>
<securityTitle>
<value>Common Stock</value>
</securityTitle>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>147</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value>By IRAs for self</value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeHolding>
</nonDerivativeTable>
<derivativeTable>
<derivativeTransaction>
<securityTitle>
<value>Options (right to buy)</value>
<footnoteId id="F1"/>
</securityTitle>
<conversionOrExercisePrice>
<value>16.4725</value>
</conversionOrExercisePrice>
<transactionDate>
<value>2003-11-26</value>
</transactionDate>
<transactionCoding>
<transactionFormType>4</transactionFormType>
<transactionCode>M</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
</transactionCoding>
<transactionTimeliness>
<value></value>
</transactionTimeliness>
<transactionAmounts>
<transactionShares>
<value>2254</value>
</transactionShares>
<transactionPricePerShare>
<value>0</value>
</transactionPricePerShare>
<transactionAcquiredDisposedCode>
<value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate>
<value>1998-11-17</value>
</exerciseDate>
<expirationDate>
<value>2003-12-07</value>
</expirationDate>
<underlyingSecurity>
<underlyingSecurityTitle>
<value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares>
<value>2254</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>0</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value></value>
</natureOfOwnership>
</ownershipNature>
</derivativeTransaction>
</derivativeTable>
<footnotes>
<footnote id="F1">Options with limited stock appreciation rights</footnote>
</footnotes>
<ownerSignature>
<signatureName>Margaret F. Murphy, on behalf of Richard C. Adkerson, pursuant to power of atty.</signatureName>
<signatureDate>2003-12-01</signatureDate>
</ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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