Proton exchange membranes for fuel cell applications were synthesized by grafting of a trifluorostyrene derivative into preirradiated poly(ethylene-alt-tetrafluoroethylene) films and subsequent hydrolysis. The monomer used for grafting was p-CF2 =CFC6H4OCF2CF2SO2F, which provided for grafted polymer chains in which both the backbone and the acid functionality are fluorinated. Emulsion and solution grafting methods and grafting in alcohol system have been performed for this monomer-base film combination. The fuel cell relevant properties were investigated and the membranes were tested in H-2/O-2 fuel cells. (c) 2006 The Electrochemical Society.