A new supercapacitor electrode material was prepared by the in situ oxidative polymerization of aniline in presence of graphene and transition metal. The structural property of the composites has been determined by Raman spectroscopy. The formation of the composites has been confirmed by field emission scanning electron microscopy and the high resolution transmission electron microscopy. The electrochemical performance of the electrode materials has been illustrated by cyclic voltammetry, electrochemical impedance spectroscopy and cyclic charge-discharge. The uniform structure together with the observed high conductivities afforded high specific capacitance and good cycling stability during the charge-discharge process when used as supercapacitor electrodes. A greater specific capacitance has been achieved in the case of cobalt doped PANI on graphene (Gr/Co/PANI) composites in comparison with HCl doped PANI on graphene composites. The Gr/Co/PANI composites showed highest specific capacitance of 989 F/g at a scan rate of 2 mV/s. The energy density of Gr/Co/PANI composites could reach 352 W h/kg at a power density of 1.581 kW/kg. (C) 2013 Elsevier B.V. All rights reserved.