The company said in a statement that it expected underlying net income for the period from January to June "to be around €3.3 billion," compared with €0.9 billion a year earlier.
The "extraordinary" rise in profits "results from the positive effect … mainly (of) the settlement with Gazprom and the discontinued negative one-off effects from the German nuclear phase-out," it said.
"These effects will also continue to show in the quarters to come," it added.
E.ON is scheduled to publish details of its first-half earnings next week.
Operating profit, as measured by earnings before interest, tax, depreciation and amortisation (EBITDA), is projected to have risen by 55.8 percent to 6.7 billion euros.
At the beginning of July, E.ON said it had reached a deal on lower gas prices with Gazprom and since having done so is sticking to its forecast for 2012, with EBITDA expected to reach up to €11 billion and net profit up to €4.5 billion.