Novel graphene based poly(vinyl alcohol)/chitosan nanocomposite membranes are prepared in this study. PVA/chitosan blend membrane (PCS91), the ratio being 9/1, is prepared by direct blend process and solution casting method and used as control in this study. The homogeneous, nonporous graphene or sulfonated graphene modified PCS membranes were prepared by casting the polymer solutions of PVA/chitosan (ratio being 9/1) with different contents of graphene or sulfonated graphene to get graphene modified PCS membranes (PCG), or sulfonated graphene modified PCS membranes (PCsG). The thermal property, KOH uptakes, ionic conductivity, and methanol permeability of the PCG and PCsG nanocomposite membranes are measured. Differential scanning calorimetry, X-ray diffraction, and thermogravimetry analysis are used for the characterization of PCG and PCsG nanocomposite membranes. The polymer electrolyte membranes are formed by immersing the various PCG and PCsG nanocomposite membranes in KOH solution and the ionic conductivity through the polymer electrolyte membrane is studied using the AC impedance technique. (C) 2015 Elsevier B.V. All rights reserved.