A new method based on a solution-grafting technique was used to prepare poly(vinylidene fluoride) grafted polystyrene sulfonated acid (PVDF-g-PSSA) proton exchange membrane. Polystyrene is easily grafted into PVDF, which has been treated in KOH solution. There is a linear relationship between the degree of grafting and the treatment time in KOH solution. Fourier transform infrared spectroscopy and differential scanning calorimetry were used to characterize the changes of the membrane's microstructure after grafting and sulfonation. The conductivity of the solution-grafted PVDF-g-PSSA membranes was investigated by the four-probe dc technique and reached 1.119 x 10(-1) S cm(-1) at 25degreesC. Gas chromatographic studies show that the methanol permeability of the PVDF-g-PSSA membrane is almost one order of magnitude lower than that of a Nafion-112 membrane. (C) 2003 The Electrochemical Society.