Rex Energy Provides Operational Update and Upcoming Conference Schedule

STATE COLLEGE, Pa., June 6, 2011 (GLOBE NEWSWIRE) -- Rex Energy Corporation (Nasdaq:REXX) is providing an operational update for each of its regions and its upcoming conference schedule. Unless specifically stated otherwise in this news release, all numbers are gross.

Appalachian Basin - Butler County, Pennsylvania

Rex Energy operates and owns a 70% working interest in its Butler operating area. The company currently has three horizontal rigs contracted for its Butler development.

In the Butler operating area, the company has completed fracture stimulation on the three well Talarico pad. These wells had a combined average five-day rate of 13.1 MMcfe per day. All three wells are currently selling natural gas and associated liquids through the Sarsen plant. The company has also fracture stimulated two wells on the McElhinney pad, which are currently flowing back. An updated well schedule is currently available on the company's website under the appendix section of the June corporate presentation.

Appalachian Basin - Westmoreland & Clearfield Counties, Pennsylvania

Williams Companies (Williams) is the operator of Rex Energy's acreage in Westmoreland and Clearfield Counties, where the company owns a 40% working interest.

In Westmoreland County, Williams recently completed fracture stimulation on the three remaining wells on the Uschak #2 pad. The three wells are currently flowing back and are expected to be placed into sales by mi-dJune. Williams has begun fracture stimulation on the three well Androstic pad and expects to be completed by mid-June. An updated well schedule is currently available on the company's website under the appendix section of the June corporate presentation.

Land Update

Rex Energy has entered into an acreage trade with Williams in the Westmoreland County and Butler operating areas. The company traded to Williams approximately 3,000 undeveloped gross acres in southeast Westmoreland County, receiving in return approximately 3,000 gross acres in the Butler operating area. The acreage received in theButler operating area is contiguous to the company's existing Butler position. AdditionallyR, ex Energy has acquired a one-year option to acquire an additional 2,400 gross acres in its Butler operating area. Costs for this acquisition are being funded out of the company's previously announced 2011 capital budget. Both transactions are within the company's AMI with its partner, Sumitomo Corporation. A reconciliation of the company's gross and net acreage position is provided in its updated investor presentation, which can be found at Rex Energy's website.

Illinois Basin — ASP Update

Rex Energy is pleased to announce increasing preliminary oil response in its Alkali-Surfactant—Polymer (ASP) Pilot at the

Bridgeport Field in Illinois. The 15-acre ASP pilot project at the Middagh Unit, which began ASP injection during August 2010,

has experienced an increase in average oil cut from 1.0 to 8.0 percent in the project area. Oil production has climbed from 16 t

82 gross barrels per day and is continuing to increase. In the first responding producing well, a steady increase from 1.5 to 18. percent oil cut was observed over the past 60 days. To date, there has been no breakthrough of the ASP chemicals, which provides increasing confidence that the project is continuing to respond appropriately.

Rex Energy previously announced an increase in the 2011 capital budget that included $3 million for expansion of the ASP flood into the 58-acre Perkins Smith project area, which is directly west of the 15-acre Middagh pilot. The company has started the brine injection pre-flush of the project area and remains on track to commence ASP injection in late fourth quarter 2011.

"While we are very encouraged by the ASP pilot performance to-date, it is still premature to estimate the eventual pore volume

oil recovery of the pilot, or translate the preliminary response into tertiary recovery proved reserves. We will continue to update the market on the pilot's production performance in subsequent operational updates," said Pat McKinney, Rex Energy's Executive Vice President and Chief Operating Officer.

Upcoming Conference Schedule

Management from Rex Energy will be participating in the following investor conferences. Presentation dates, times and webcas availability are all subject to change at the discretion of the conference organizer. Please refer to theRex Energy website for further details on these conferences and other upcoming events.

Conference City Date Presentation

Time

Webcast

Available

RBC Capital Markets Global Energy & Power Conference

New York

City, NY 6/7/201 2:35 pm E

Please refer to Rex Energy website for webcast link.

RBC Capital Markets Global Energy & Power Conference Panel

Discussion — Appalachian Shale

New York

City, NY 6/7/2011 12:35 pm ET N/A

The presentation for the events listed above will be available on the Investor Relations section of the Rex Energy website, www.rexenergy.comunder Events & Presentations. The presentations will be posted no later than 24 hours prior to the presentation time and will remain available for thirty days after the event.

About Rex Energy Corporation

Rex Energy is headquartered in State College, Pennsylvania and is an independent oil and gas company operating in the Appalachian, Illinois and Denver-Julesburg Basins within the United States. The company's strategy is to pursue its higher potential exploration drilling prospects while acquiring oil and natural gas properties complementary to its portfolio.

The Rex Energy Corporation logo is available at http://www.globenewswire.com/newsroom/prs/?pkgid=5489

Forward-Looking Statements

Except for historical information, statements made in this release, including those relating to capital expenditures, production growth, planned number of wells, timing of rig operations, fracture stimulation activities, completion of wells, expected dates that wells are producing hydrocarbons that are sold, and expected timing for the expanded ASP pilot, are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of

1934, as amended. These forward-looking statements are indicated by words such as "expected", "expects", "anticipates" and similar words. These statements are based on assumptions and estimates that management believes are reasonable based on currently available information; however, management's assumptions and the company's future performance are subject to a wide range of business risks and uncertainties, and there is no assurance that these goals and projections can or will be met. Any number of factors could cause actual results to differ materially from those in the forward-looking statements, including (without limitation) the following: