DAYTON — DPL Inc., owner of Dayton Power and Light Co., said its third-quarter earnings increased by 27 percent to $86.4 million as hot weather kept air conditioners running and drove up electricity consumption.

Earnings per share for the three months ended Sept. 30 were 74 cents, up 27 percent from 59 cents in the third quarter of 2009, DPL said Thursday. Revenues totaled $516.9 million, up from $407.3 million a year ago.

“We had a solid quarter driven by sustained hot weather and improved economic conditions, and we remain on track to achieve our 2010 earnings estimates,” said Paul Barbas, DPL’s president and chief executive officer.

The company achieved the higher earnings despite increased costs of coal and natural gas fuel for generating plants and higher costs of buying additional electricity from outside sources to meet peak demands, management said.

For the first nine months of 2010, earnings were $1.88 per share, up from $1.58 during the same period of 2009. Revenues increased to $1.41 billion, up 19 percent from $1.18 billion last year.

DPL’s management affirmed its expectation that the company will earn between $2.35 and $2.55 per share for 2010. Management expects earnings of between $2.30 and $2.55 per share in 2011.

On Wednesday , DPL’s board of directors approved a plan to buy back up to $200 million of the company’s common stock, over time. Companies buy back stock in order to prop up share prices, and to keep controlling interest within the company.

Contact this reporter at (937) 225-2242 or jnolan@DaytonDailyNews.com.