Proton-conducting materials based on the MF-4SK membrane and polyantimonic acid have been synthesized; their dielectric properties and conductivity at varying temperature and relative air humidity have been studied. The introduction of polyantimonic acid particles leads to a significant increase in the proton conductivity of the membranes-from 3.2 x 10(-5) to 2.5 x 10(-4) S/cm-at low humidity. Studies of the proton conductivity as a function of temperature have shown that the doping of the MF-4SK membrane with polyantimonic acid leads to a decrease in the activation energy from 16.8 to 12.9 kJ/mol.