This work demonstrated a novel and simple route for preparing a composite comprising of manganese oxide (MnO2) nanoparticles and polyaniline (PANI) doped poly(4-styrene sulfonic acid-co-maleic acid) (PSSMA) by "electrochemical doping-deposition". The PANI-PSSMA-MnO2 composite was characterized by scanning electron microscopy (SEM)), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). SEM images revealed a uniform dispersion of MnO2 nanoparticles ill the porous Structure of PANI-PSSMA structure. XRD measurements showed the distortion of the crystal structure of beta-MnO2 after deposition Of MnO2 in PANI-PSSMA structure. Thus, the XRD pattern of PANI was predominating. Cyclic voltammetry and chronopotentiometry were employed in 0.5 M Na2SO4 to evaluate the capacitor properties. The results showed a significant improvement in the specific capacitance of the composite electrode. The specific capacitance of PANI-PSSMA-MnO2 (50.4 Fg(-1)) had improvement values of 172% compared to that of PANI (18.5 Fg(-1)). When only the MnO2 mass was considered, the composite had a specific capacitance of 556 Fg(-1). (C) 2009 Elsevier B.V. All rights reserved