dc electrical conductivity at surface of gamma-irradiated polyaniline (PAn) has been studied. EPR spectroscopic results indicate that the variation of spin concentration is consistent with the increase of sigma(dc). Electrical conductivity (sigma(dc)) versus temperature M characteristics of unirradiated and irradiated PAn were performed, which demonstrate that the unirradiated curve can fit to lnsigma(dc) is-proportional-to T-1, while the irradiated curve fit to lnsigma(dc) is-proportional-to T-1/4.