Hybrid films of polyaniline (PANI) and manganese oxide (MnOx,) were obtained through potentiodynamic deposition from solutions of aniline and MnSO4 at pH 5.6. The hybrid films demonstrated characteristic redox behaviors of PANI in acidic aqueous solution. Characterization of the hybrid films by XRD indicated the amorphous nature of MnOx in the films in which manganese existed in oxidation states of +2, +3 and +4, based on XPS measurement. Hybrid film of PANI and MnOx, PM120 obtained from the solution of 0.1 M aniline and 120 mM Mn2+ displayed a well opened nanofibrous structure which showed an 44% increase in specific capacitance from that of PANI (408 F g(-1)) to 588 F g(-1), measured at 1.0 mA cm(-2) in 1 M NaNO3 (pH 1). The hybrid film kept more than 90% of its capacitance after 1000 charging-clischarging cycles, with a coulombic efficiency of 98%. The specific capacitance of a symmetric capacitor using PM120 as the electrodes is 112 F g(-1). (C) 2007 Elsevier Ltd. All rights reserved.