The conductivity relaxation of 1-methyl-2-pyrrolidone (NMP)-plasticized polyaniline (PAn) film was measured using dielectric analysis (-50 to +250 degrees C, 0.4-10(5) Hz). The complex electric modulus (M*) representation of the results of dielectric measurement of NMP-plasticized PAn film exhibits two relaxation peaks, which is contrary to the single relaxation. peak of the PAn powder (free from NMP). This implicates a two-phase interwoven network structure of the film, which is supported by the results from UV-vis spectroscopy (-50 to +250 degrees C) and near-field scanning optical microscopy of the NMP-plasticized PAn film and from the conductivity relaxations of the model compounds : the fully oxidized and fully reduced forms of PAn powder. The peak at lower frequency is due to the conductivity relaxation of the phase with oxidized repeat units and that at higher frequency to the relaxation of the phase with reduced repeat units. The conductivity of the phase of reduced repeat units is higher than that of the phase of oxidized repeat units.