A new composite proton exchange membrane was made by casting a polystyrene sulfonate (PSS) solution with suspended micron sized particles of a crosslinked PSS ion exchange resin. The chemical compatibility of the resin and the PSS allow stable composites with up to 50 wt.% resin. The resin/PSS composite membranes have greater ion exchange capacity than PSS membranes, but the ion conductivity is similar to that of PSS. Swelling of the composite membranes as a function of water uptake is lower than that of PSS. The composite membranes are mechanically more robust and display greater chemical stability in a fuel cell than the PSS membranes. The polarization curves show long-term degradation of the membranes; the cell potential decreased by 60% in 55 It for a PSS membrane, and in 340 h for a composite membrane. The reduced rate of degradation of the composite membranes suggests that with further refinement they may have potential as an inexpensive alternative for PEM fuel cells. (C) 2004 Elsevier B.V. All rights reserved.