Kosmos Energy Announces Closing of Secondary Public Offering of Common Shares

Kosmos Energy Ltd. (“Kosmos”) (NYSE: KOS) announced today the closing of the previously announced registered underwritten public offering of 15 million common shares (the “Offering”) from funds affiliated with The Blackstone Group L.P. and Warburg Pincus LLC (the “Selling Shareholders”). The underwriter of the Offering was granted an option, exercisable within 30 days, to purchase up to an additional 2.25 million common shares from the Selling Shareholders on the same terms and conditions to cover over-allotments, if any. Kosmos will not receive any of the proceeds from the sale of the common shares. Citigroup Global Markets Inc. acted as the underwriter of the Offering.

The Offering was made pursuant to an effective shelf registration statement, including a prospectus, filed by Kosmos with the U.S. Securities and Exchange Commission (“SEC”) on June 22, 2012. Before you invest, you should read the prospectus in that registration statement and other documents Kosmos has filed with the SEC for more complete information about Kosmos and the Offering. You may get these documents for free by visiting the SEC website at www.sec.gov. Alternatively, copies of the prospectus and a prospectus supplement, when available, may be obtained from Citigroup Global Markets Inc., c/o Broadridge Financial Solutions, 1155 Long Island Avenue, Edgewood, New York 11717, or by telephone at 1-800-831-9146, or by email at prospectus@citi.com.

About Kosmos Energy

Kosmos Energy is a leading independent oil and gas exploration and production company focused on frontier and emerging areas along the Atlantic Margin.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements, other than statements of historical facts, included in this press release that address activities, events or developments that Kosmos expects, believes or anticipates will or may occur in the future are forward-looking statements. Kosmos’ estimates and forward-looking statements are mainly based on its current expectations and estimates of future events and trends, which affect or may affect its businesses and operations. Although Kosmos believes that these estimates and forward-looking statements are based upon reasonable assumptions, they are subject to several risks and uncertainties and are made in light of information currently available to Kosmos. When used in this press release, the words “anticipate,” “believe,” “intend,” “expect,” “estimate,” “plan,” “will” or other similar words are intended to identify forward-looking statements. Such statements are subject to a number of assumptions, risks and uncertainties, many of which are beyond the control of Kosmos, which may cause actual results to differ materially from those implied or expressed by the forward-looking statements. Further information on such assumptions, risks and uncertainties is available in Kosmos’ Securities and Exchange Commission (“SEC”) filings. Kosmos undertakes no obligation and does not intend to update or correct these forward-looking statements to reflect events or circumstances occurring after the date of this press release, except as required by applicable law. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release. All forward-looking statements are qualified in their entirety by this cautionary statement.