Proton conducting composite electrolytes based on zeolites dispersed in poly(tetrafluoroethylene) matrix are synthesized and characterized. The ionic conductivity of these composites is analyzed in connection with such features as a sorption of solvents and tensile strength of the composite membrane. Electrolytes exhibiting the highest conductivities are tested in model methanol/oxygen fuel cell working at 70 degrees C. The current densities obtained exceeded 50 mA/cm(2) with the power densities = similar to 4 mW/cm(2).