Fuel cells could become the main power source for small general aviation aircraft or could replace APU and internal sub-systems on larger aircraft, to obtain all-electric or more-electric air vehicles. There are several potential advantages of using such a power source, that range from environmental and economic issues to performance and operability aspects. A preliminary design is reported. Also, the paper contains a description of testing activities related to experimental flights of an all-electric general aviation aircraft fueled by hydrogen. Great importance has been given to the testing phase of the prototype and examples of each testing stage are shown ranging from the single components to the final test flights. During the 6 experimental flights a rotation speed of 84 km/h was obtained in 184 m of taxi at power of 35 kW. Level flight was attained at 135 km/h and endurance of 39 min by mean of only a fuel cell power setting (speed world record for the FAI Sporting Code Category C - airplane). Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.