A composite of reduced Graphene oxide -polyaniline (RGO-PANI) was fabricated by an in situ electrochemical oxidative polymerization of aniline in the presence of GO in Sodium dodecyl sulfate (SDS), which synthsized by anodic exfoliation, on carbon paper electrode. Here GO uses as a protonation agent for doping of PANI and also as a physical crosslinker of PANI fibers. The structure and the property of RGO-PANI composite were investigated by tunneling electron microscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, cyclic voltammetry, galvanostatic charge–discharge test and electrochemical impedance spectroscopy (EIS) techniques. The fabricated composite was then employed as the supercapacitor, which provides specific capacitances as high as 890 F g−1 at the current density of 1 A g−1 in 1 M H2SO4 aqueous solution. Long term stability and high specific capacitance, are related to synergistic effects between PANI and RGO and also conductive graphene sheets. EIS indicates a decreasing charge transfer resistance at the electrode/electrolyte interface of RGO-PANI composite than each individual component. This work may suggest an alternative method to synthesis one-pot produce of RGO-PANI composite for the development of high-performance supercapacitors.