The electropolymerization process of bithienyl (BT) in electrolyte solutions of acetonitrile and propylencarbonate at Pt-, Ni-and Ti-electrodes has been systematically studied by means of cyclic voltammetry and potential step chronoamperometry methods. The well-reproducible cyclic voltammograms (CVGs) indicate that the mechanism of BT electropolymerization is independent of the solvent and electrode material. From Tafel plots with a slope of 61 f 2 mV electrochemical parameters such as I$, u, n and io of the BT oxidation were determined. The charge QEl for chain growth of the polymer is proportional to BT concentration, to the number of sweeps and to the reverse potential. The degree of oxidation d& of the PBT can be determined through the charge Qnr and the charge Q & of the PBT oxidation. The ratio Q&/err us the number of sweeps yields a straight line giving d& < 0.45 at the stationary electrode and d& < 0.66 at the rotating disk electrode, respectively. The formation process of the PBT films was observed by means of REM. The film formation undergoes nucleation, spherical nuclei growth in three dimensions and their overlapping each other to form a layer. This process is repeated layer by layer. The BT diffusion coefficient is calculated from the current response to large potential steps.