WASHINGTON - Pepco, a subsidiary of Pepco Holdings, Inc., today announces that the District of Columbia Public Service Commission (DCPSC) has authorized a decrease in supply rates. Based on the results of a competitive auction, customers who buy their electricity through the Standard Offer Service (SOS) program will see decreases in their electricity bills beginning June 1, 2011. SOS represents about 71 percent of a residential customer's bill. The change will decrease average monthly residential electricity bills by about 10.7 percent. The average residential customer uses about 754 kWh per month in the summer and 614 kWh per month in the winter. The monthly bill for an average residential SOS customer will decrease by $10.46 adjusting the average bill from $97.88 to $87.42.

The supply cost of electricity (including generation and transmission) for SOS customers will decline from 11.56 cents per kWh in the summer to 9.90 cents and from 10.90 cents per kWh in the winter to 9.44 cents per kWh. As a result the supply portion of the average residential electricity bill will decline from $75.38 to $64.92. The average monthly residential bill (including supply and delivery charges) will be about $87.42.

The SOS Program is administered by Pepco under rules established by the DCPSC. Under legislation passed by the D.C. Council in 1999, Pepco itself no longer owns any power plants. The DCPSC has designated Pepco to purchase electricity for SOS customers through power supply contracts in an annual auction.

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Pepco, a subsidiary of Pepco Holdings, Inc. (NYSE: POM), delivers safe, reliable and affordable electric service to more than 778,000 customers in Maryland and the District of Columbia.