A novel composite membrane was prepared by incorporation of silica-included phosphotungstic acid (PWA) additive into perfluorosulfonic acid (PFSA) followed by solution casting. Physico-chemical properties of the composite membranes were studied by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry analysis (TGA), water uptake and swelling ratio. The results of FT-IR and TGA illustrated the stability of the PWA-silica additive in the PFSA matrix. Lower PWA-silica additive loading (2.5 and 5 wt%) in the composite membranes helped to inhibit methanol crossover and enhance the proton conductivity. However, higher additive content shows decrease in both methanol resistance and proton conductivity.