<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-12-12</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000101778</issuerCik>
        <issuerName>MARATHON OIL CORP</issuerName>
        <issuerTradingSymbol>MRO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001238369</rptOwnerCik>
            <rptOwnerName>BEHRMAN PHILIP G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MARATHON OIL CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>5555 SAN FELIPE ROAD</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77056</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Sr. Vice Pres., WW Exploration</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2007-12-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
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            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
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                </transactionShares>
                <transactionPricePerShare>
                    <value>23.825</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
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                    <footnoteId id="F1"/>
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            </postTransactionAmounts>
            <ownershipNature>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
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                </transactionShares>
                <transactionPricePerShare>
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                <transactionPricePerShare>
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        <nonDerivativeTransaction>
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        <nonDerivativeTransaction>
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                <transactionPricePerShare>
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        <nonDerivativeTransaction>
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                    <value>97489.907</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>COMMON STOCK</value>
            </securityTitle>
            <transactionDate>
                <value>2007-12-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>766.000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>59.63</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>96723.907</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>EMPLOYEE STOCK OPTION (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>23.825</value>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-12-12</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>30266.00</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2006-05-25</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-05-25</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>COMMON STOCK</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>30266.00</value>
                    <footnoteId id="F2"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15134.00</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On June 18, 2007, the common stock of Marathon Oil Corporation split 2-for-1 for holders of record on May 23, 2007, resulting in
the reporting person's ownership of 48,321.45 additional shares of common stock</footnote>
        <footnote id="F2">This option was previously reported as covering 22,700 shares at an exercise price of $47.65, but was adjusted to reflect the 2-f
or-1 stock split that occurred on June 18, 2007.</footnote>
        <footnote id="F3">Vests in three cumulative annual installments of 15,133, 15,133, and 15,134 shares on May 25, 2006, 2007, and 2008, respectively.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>R. J. Kolencik, Attorney-in-Fact for Philip G. Behrman</signatureName>
        <signatureDate>2007-12-13</signatureDate>
    </ownerSignature>
</ownershipDocument>
[{"type": "4", "sequence": "1", "filename": "doc4.xml", "description": "PRIMARY DOCUMENT", "secsgml_size_bytes": 37042}]
X0202
4
2007-12-12
0
0000101778
MARATHON OIL CORP
MRO
0001238369
BEHRMAN PHILIP G
C/O MARATHON OIL CORPORATION
5555 SAN FELIPE ROAD
HOUSTON
TX
77056
0
1
0
0
Sr. Vice Pres., WW Exploration
COMMON STOCK
2007-12-12
4
M
0
30266.000
23.825
A
126989.907
D
COMMON STOCK
2007-12-12
4
S
0
11300.000
59.42
D
115689.907
D
COMMON STOCK
2007-12-12
4
S
0
1300.000
59.43
D
114389.907
D
COMMON STOCK
2007-12-12
4
S
0
800.000
59.44
D
113589.907
D
COMMON STOCK
2007-12-12
4
S
0
2100.000
59.45
D
111489.907
D
COMMON STOCK
2007-12-12
4
S
0
2400.000
59.46
D
109089.907
D
COMMON STOCK
2007-12-12
4
S
0
2400.000
59.47
D
106689.907
D
COMMON STOCK
2007-12-12
4
S
0
1100.000
59.48
D
105589.907
D
COMMON STOCK
2007-12-12
4
S
0
2100.000
59.49
D
103489.907
D
COMMON STOCK
2007-12-12
4
S
0
700.000
59.50
D
102789.907
D
COMMON STOCK
2007-12-12
4
S
0
1100.000
59.51
D
101689.907
D
COMMON STOCK
2007-12-12
4
S
0
800.000
59.52
D
100889.907
D
COMMON STOCK
2007-12-12
4
S
0
100.000
59.53
D
100789.907
D
COMMON STOCK
2007-12-12
4
S
0
500.000
59.55
D
100289.907
D
COMMON STOCK
2007-12-12
4
S
0
400.000
59.56
D
99889.907
D
COMMON STOCK
2007-12-12
4
S
0
100.000
59.57
D
99789.907
D
COMMON STOCK
2007-12-12
4
S
0
200.000
59.58
D
99589.907
D
COMMON STOCK
2007-12-12
4
S
0
800.000
59.59
D
98789.907
D
COMMON STOCK
2007-12-12
4
S
0
400.000
59.60
D
98389.907
D
COMMON STOCK
2007-12-12
4
S
0
300.000
59.61
D
98089.907
D
COMMON STOCK
2007-12-12
4
S
0
600.000
59.62
D
97489.907
D
COMMON STOCK
2007-12-12
4
S
0
766.000
59.63
D
96723.907
D
EMPLOYEE STOCK OPTION (Right to Buy)
23.825
2007-12-12
4
M
0
30266.00
0
D
2006-05-25
2015-05-25
COMMON STOCK
30266.00
15134.00
D
On June 18, 2007, the common stock of Marathon Oil Corporation split 2-for-1 for holders of record on May 23, 2007, resulting in
the reporting person's ownership of 48,321.45 additional shares of common stock
This option was previously reported as covering 22,700 shares at an exercise price of $47.65, but was adjusted to reflect the 2-f
or-1 stock split that occurred on June 18, 2007.
Vests in three cumulative annual installments of 15,133, 15,133, and 15,134 shares on May 25, 2006, 2007, and 2008, respectively.
R. J. Kolencik, Attorney-in-Fact for Philip G. Behrman
2007-12-13