In this study, novel cross-linked nanocomposite membranes have been prepared from poly(vinyl alcohol) (PVA) and aryl sulfonated graphene oxide (SGO) and a way of cross-linking to improve the chemical, thermal, and mechanical stabilities of the nanocomposite was adopted. The surface of the graphene oxide nanoparticles was modified by aryl diazonium salt of sulfanilic acid. It was revealed that addition of SGO (5 wt?%) into the PVA matrix improves the thermal stability (melting temperature, T-m = 223 degrees C), mechanical stability (tensile strength, TS = 67.8 MPa) and proton conductivity (sigma = 0.050 S cm1) of the nanocomposite proton exchange membranes. A proton exchange membrane fuel cell (PEMFC) fabricated with the PVA/SGO membrane showed a maximum power density of 16.15 mW cm2 at 30 degrees C. As a result, the investigated PVA/SGO nanocomposite membranes have good potential for further studies and applications in PEMFCs.