A series of proton-conducting composites has been synthesized from PVA/PAMPS [poly(vinyl alcohol)/poly(2-acrylamido-2-methyl-1-propanesulfonic acid)] using high molecular weight PVA (HMw-PVA). By applying high molecular weight PVA as a polymer matrix, a greater hydrophobicity of the membranes emerged, which endows them with reduced water uptake (70-90%) but high proton conductivity (0.06-0.1 S cm(-1)), low methanol permeability (1/3 to 1/5 that of Nafion 117), and excellent oxidative stability towards Fenton's reagent. A DMFC fabricated with the above membrane showed a high power density of 15.8 mW cm(-2) at 30 degrees C, which reached 42.9 mW cm(-2) at 80 degrees C. An initial lifetime performance assessment in DMFC mode yielded a value of 70 h for stable cell operation. (C) 2009 Published by Elsevier B.V.