Marathon Oil Corporation Chairman, President and CEO, Clarence P. Cazalot, Jr., to Retire Dec. 31, 2013 - Lee M. Tillman Elected

Marathon Oil Corporation Chairman, President and CEO, Clarence P. Cazalot,
Jr., to Retire Dec. 31, 2013 - Lee M. Tillman Elected President and CEO
effective Aug. 1, 2013

HOUSTON, June 13, 2013 (GLOBE NEWSWIRE) -- Clarence P. Cazalot, Jr, chairman,
president and CEO of Marathon Oil Corporation (NYSE: MRO) has elected to
retire on Dec. 31, 2013, after almost 14 years leading Marathon Oil and 41
years in the oil and gas industry. Cazalot will continue as executive chairman
through Dec. 31, 2013. The Marathon Oil board of directors has elected Lee M.
Tillman to the board of directors and to succeed Cazalot as president and CEO
effective Aug. 1, 2013. The board of directors intends to nominate Dennis H.
Reilley, currently Marathon Oil lead director, as non-executive chairman upon
Cazalot's retirement.

Tillman, 51, most recently served as vice president of Engineering for
ExxonMobil Development Company where he was responsible for all global
engineering staff engaged in major project concept selection, front end design
and engineering. He holds a Bachelor of Science degree in chemical engineering
with honors from Texas A&M University and a Ph.D. in chemical engineering from
Auburn University. Following his formal education, Tillman began his career in
the oil and gas industry at Exxon in 1989 as a research engineer. He has
extensive operations management and leadership experience that has included
assignments in Jakarta, Indonesia; Aberdeen, Scotland; Stavanger, Norway;
Malabo, Equatorial Guinea; Dallas and New Orleans.

"Speaking for the entire Marathon Oil board of directors, we are very pleased
to welcome Lee to the Company.His strong leadership skills and extensive
experience in global operations, project execution and leading edge technology
will be invaluable in confronting the challenges facing our Company and
industry," said Cazalot."I look forward to working with Lee, the rest of our
executive leadership team, and all our dedicated employees over the next six
months as we transition to his leadership and continue to execute on our well
defined strategy."

"Marathon Oil's strong set of base and growth assets, along with a robust
exploration portfolio, reputation in the industry as a valued partner and
dedication to exemplary corporate values make this a position I am very proud
and excited to accept," said Tillman. "The progress Marathon Oil has made
moving from an integrated company to an independent exploration and production
company over the past two years has been nothing short of exceptional.The
combined efforts of a dynamic board, focused management and dedicated global
employees have yielded Marathon Oil's differentiating performance and strong
growth outlook.I look forward to building on this solid foundation to further
enhance Marathon Oil's long term shareholder value."

Marathon Oil Corporation is an international exploration and production
company. Based in Houston, Texas, the Company had net proved reserves at the
end of 2012 of 2 billion barrels of oil equivalent in North America, Europe
and Africa. For more information, please visit the Company's website at
http://www.marathonoil.com.

Note to Editors:

Lee Tillman's bio is included below. Bios for Clarence Cazalot and Dennis
Reilley are available online at
http://www.marathonoil.com/About_Us/Board_of_Directors/. Photos are available
upon request.

Lee M. Tillman

Lee M. Tillman is joining Marathon Oil Corporation Aug. 1, 2013, as president
and CEO. Since 2010, he has been vice president of Engineering for ExxonMobil
Development Company where he was responsible for all global engineering staff
engaged in major project concept selection, front end design and engineering.
He holds a Bachelor of Science degree in chemical engineering with honors from
Texas A&M University and a Ph.D. in chemical engineering from Auburn
University.

Following his formal education, Tillman began his career in the oil and gas
industry at Exxon in 1989 as a research engineer.

Tillman progressed through positions of increasing responsibility in Houston;
New Orleans; Jakarta, Indonesia; and Aberdeen, Scotland. He assumed the
position of operations superintendant, New Orleans Production Organization in
1998, and was named operations manager, Mobil Equatorial Guinea relocating to
Malabo, Equatorial Guinea in 2001.

In 2003, Tillman moved to Irving, Texas as upstream advisor to the ExxonMobil
management committee. Relocating to Houston in 2005, he was appointed offshore
division manager, ExxonMobil Upstream Research Company. From 2006 to 2007, he
served as acting vice president, ExxonMobil Upstream Research Company.

From 2007 to 2010, Tillman served as North Sea production manager and lead
country manager in Stavanger, Norway.

Tillman is a member of the Society of Petroleum Engineers.

CONTACT: Media Relations Contacts: 
         Lee Warren 713-296-4103
         John Porretto 713-296-4102
        
         Investor Relations Contacts:
         Howard Thill 713-296-4140
         Chris Phillips 713-296-3213
 
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