Nafion-based composite solid polyelectrolytes containing fullerene C₆₀ and its water-soluble derivatives fullerenol-C₆₀ and tris-malonate-C60 were studied by the impedance spectroscopy method. It was found that introduction of these dopants in Nafion leads to a substantial increase in proton conductivity of the composites in the region of low relative humidity. The reasons for the influence of dopants on proton conductivity of composites were discussed.