The concept of a proton conducting, methanol impermeable composite electrolyte system is demonstrated. A three-layered laminar electrolyte consisting of a dense, methanol impermeable protonic conductor sandwiched between proton permeable electronically insulating layers permits the selective transport of protons while eliminating methanol crossover to the cathode. We demonstrate the selectivity of the composite electrolyte using palladium foil sandwiched between two Nafion(TM) polymer membranes. The open-circuit voltage for an H-2/O-2 fuel cell utilizing this composite electrolyte is unaffected by introduction of methanol to the H, fuel stream, whereas conventional polymer electrolyte cells suffer severe degradation of performance due to methanol crossover.