Ownership Submission
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 OF SECURITIES

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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(Print or Type Responses)
1. Name and Address of Reporting Person *
CAZALOT CLARENCE P JR
  2. Issuer Name and Ticker or Trading Symbol
MARATHON OIL CORP [MRO]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
President and CEO
(Last)
(First)
(Middle)
C/O MARATHON OIL CORPORATION, 5555 SAN FELIPE ROAD
3. Date of Earliest Transaction (Month/Day/Year)
08/11/2005
(Street)

HOUSTON, TX 77056
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ 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 (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 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 08/11/2005   M   100,000 A $ 23.4063 445,637 D  
COMMON STOCK 08/11/2005   M   140,000 A $ 32.52 585,637 D  
COMMON STOCK 08/11/2005   M   240,000 A $ 28.12 825,637 D  
COMMON STOCK 08/11/2005   D   480,000 D $ 63.55 (1) 345,637 D  

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 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
(Month/Day/Year)
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
EMPLOYEE STOCK OPTION (Right to Buy) $ 32.52 08/11/2005   M(2)     140,000 05/29/2002 05/29/2011 COMMON STOCK 140,000 $ 0 0 D  
STOCK APPRECIATION RIGHT $ 32.52 08/11/2005   M(2)     140,000 05/29/2002 05/29/2011 COMMON STOCK 140,000 $ 0 0 D  
EMPLOYEE STOCK OPTION (Right to Buy) $ 23.4063 08/11/2005   M(2)     100,000 03/03/2005 03/03/2010 COMMON STOCK 100,000 $ 0 0 D  
EMPLOYEE STOCK OPTION (Right to Buy) $ 28.12 08/11/2005   M(2)     240,000 05/28/2003 05/28/2012 COMMON STOCK 240,000 $ 0 0 D  
STOCK APPRECIATION RIGHT $ 23.4063 08/11/2005   M(2)     100,000 03/03/2005 03/03/2010 COMMON STOCK 100,000 $ 0 0 D  
STOCK APPRECIATION RIGHT $ 28.12 08/11/2005   M(2)     240,000 05/28/2003 05/28/2012 COMMON STOCK 240,000 $ 0 0 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
CAZALOT CLARENCE P JR
C/O MARATHON OIL CORPORATION
5555 SAN FELIPE ROAD
HOUSTON, TX 77056
  X     President and CEO  

Signatures

 R. J. Kolencik, Attorney-in-Fact for Clarence P. Cazalot, Jr   08/15/2005
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Under the terms of the Stock Appreciation Right, the Stock Appreciation Right will be adjusted to reflect the highest fair market value of Marathon Oil Corporation Common Stock during the ten day trading period commencing August 2, 2005. This Form 4 will be amended if the highest fair market value exceeds the highest fair market value as of August 11, 2005, which is $63.55.
(2) Exercise of tandem SAR and cancellation of underlying stock option.

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