E.ON, Germany's biggest power supplier, said on Wednesday it returned to profit in 2012, when it booked net profit of 2.217 billion euros ($2.9 billion) compared with a loss of 2.219 billion euros a year earlier.
Underlying net profit, which includes one-off effects, soared by 67 percent to 4.187 billion euros.
And operating profit, as measured by earnings before interest, tax, depreciation and amortisation (EBITDA) climbed by 16 percent to 10.786 billion euros on a 17-percent increase in revenues to 132.09 billion euros, E.ON said in its 2012 anual report.
Chief executive Johannes Teyssen described E.ON's performance as "solid".
One of the main reasons for the rise in underlying earnings was a significant improvement in the gas wholesale business following the renegotiation of gas-procurement contracts with producers, he said.
In addition, 2011 earnings had been adversely affected by one-off items relating to Germany's accelerated phaseout of nuclear energy.
Additional generating capacity in Russia and the cost-cutting measures "were also positive factors," while negative factors included lower prices and sale volume in the power business, E.ON continued.
Looking ahead to the current year, E.ON said it expects to achieve EBITDA of 9.2-9.8 billion euros.
"This forecast factors in the loss of earnings streams through asset sales under our ongoing divestment programme," it said.
Underlying net profit was projected to come in at 2.2-2.6 billion euros.