In this study, homogenous and flexible conductive polymer films with improved mechanical properties were obtained by the electrochemical polymerization of aniline on polycarbonate-coated 316 steel electrodes. The optimal thickness of polycarbonate coating was found to be 20 mu m in order to obtain free-standing, high-quality conducting films. The polyaniline/polycarbonate films obtained on 316 steel electrodes were more homogenous than those obtained on platinum electrodes. The maximum conductivity was observed for 10% polyaniline content; increasing the polyaniline content did not affect the conductivity to a significant extent. The films were found to be a suitable sensor against ammonia gas in a concentration range of 0.1-1.0%.