A single-step method for preparation of sulfonic acid proton exchange membranes (PVDF-g-PSSA) by grafting of sodium styrene sulfonate (SSS) onto electron beam irradiated poly(vinylidene fluoride) (PVDF) was studied. The microstructure of the obtained membranes was characterized using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The properties of the membranes such as water uptake, ionic conductivity and the degree of crystallinity were investigated as a function of ion exchange capacity (IEC). The new method showed to be promising in improving the properties of the membranes and reducing their cost of fabrication. (C) 2009 Elsevier B.V. All rights reserved.