Powder samples of hydrogen molybdenum bronzes (H2MoO3) were effectively stabilized by the addition of 30 mass-% polyethylene (PE) powder, pressing and a following thermal treatment. The composite material does not degrade in 0.05 M H2SO4 so that cyclic voltammetry (CV) and impedance analysis could be carried out in 0.05 M H2SO4. The high frequency parts of the impedance spectra are characterized by strongly depressed semicircles, indicating that the charge transfer reaction cannot be described by one charge transfer resistance and one double layer capacity (parallel RC-element). In the low frequency range hydrogen diffusion in the bronze crystals governs the shape of the spectra.