Simultaneous gamma irradiation was proved to be an effective tool for ethylene/chlorotrifluoroethylene grafting by styrene and vinyl pyrrolidone with different ratios. It was found that; the optimum grafting yield was 81% by using 40 kGy gamma irradiation dose when the binary monomers ratio was 1: 1 (styrene: vinyl pyrrolidone). The grafted membranes were investigated for chemical structure by FT-IR and thermal properties by thermal gravimetric analysis. The mechanical properties were studied by measuring tensile strength while morphological structure was characterized by scanning electron microscope. The membranes' free volume sizes were determined using positron annihilation lifetime spectroscopy (PALS). Ion exchange capacity, water uptake and membranes thickness were investigated and proton conductivity was evaluated. The optimum temperature for attaining the maximum fuel cell performance was at 75 degrees C while it reduced by decreasing the temperature to 50 degrees C or increasing it to 85 degrees C. The fuel cell performance based highest yield of the grafted membrane was more durable than compressed Nr. 118 (commercial membranes) up to 450 hours. (C) 2015 Elsevier Ltd. All rights reserved.