According to Official Guinness Records,
For the first time in aviation history, a manned aircraft powered by hydrogen fuel cells was successfully flown in February and March 2008. The aircraft was a two-seat Dimona motor glider, and the flights took place at an airfield at Ocana, south of Madrid, Spain. It was the result of work by an engineering team at Boeing Research and Technology Europe (BR&TE) together with industry partners in Austria, France, Germany, Spain, the United Kingdom and the United States.
The two-seat Dimona motor-glider, built in Austria by Diamond Aircraft Industries, has a 16.3 metre (53.5ft) wingspan and a modified BR&TE Proton Exchange Membrane fuel cell/lithium battery hybrid system, which powers an electric motor coupled to a conventional propeller.
For a complete list of 2008 records, please visit 2008 Guinness Records in Spain.