Sulfonation of cPTFE Film grafted Styrene for Proton Exchange Membrane Fuel Cell. Sulfonation of γ-rayiradiated and styrene-grafted crosslinked polytetrafluoroethylene film (cPTFE-g-S film) have been done. The aim of theresearch is to make hydropyl membrane as proton exchange membrane fuel cell. Sulfonation was prepared withchlorosulfonic acid in chloroethane under various conditions. The impact of the percent of grafting, the concentration ofchlorosulfonic acid, the reaction time,and the reaction temperature on the properties of sulfonated film is examinated.The results show that sulfonation of surface-grafted films is incomplete at room temperature. The increasing ofconcentration of chlorosulfonic acid and reaction temperature accelerates the reaction but they also add favor sidereactions. These will lead to decreasing of the ion-exchange capacity, water uptake, and proton conductivity butincreasing the resistance to oxidation in a perhidrol solution. The cPTFE-g-SS membrane which is resulted has stabilityin a H2O2 30% solution for 20 hours.