Electrochemical impedance spectroscopy was applied for characterization of hybrid thin films consisting of poly(3,4-ethylenedioxythiophene) and nickel, cobalt and iron hexacyanoferrates (pEDOT/Mehcf). Films were tested in contact with aqueous KCl electrolyte in a temperature range from 283 to 313 K. Impedance spectra show that tested hybrid systems are stable and diffusion impedance is characterized by two elements of different time constants, indicating presence of two separate charge fluxes. Hybrid materials exhibit higher ionic conductivity in comparison with pure inorganic Mehcf films. Electroactive polymer chains in the film cause enhancement in the electric conductivity of the material. (c) 2007 Elsevier B.V. All rights reserved.