Manganese dioxide (MnO2) nanowires with diameter about 30-70 nm is achieved via a two-step process: first, template-free cathodic electrodeposition from aqueous solution of Mn(NO3)(2) on steel substrate and followed by heat treatment. The temperature-annealed sample was studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) methods and Fourier transform infrared (FT-IR) spectroscopy. The electrochemical performance of the MnO2 sample was studied by cyclic voltammetry (CV) and chronopotentiometry in Na2SO4 solutions. The sample showed excellent supercapacitive behavior. The specific capacitance (SC) of 237 F g(-1) in a potential window of 0-0.9V was obtained at the scan rate of 2 mV s(-1). The SC calculated from the chronopotentiometry data is about 246 F g(-1). The SC was decreased by 16% after 1000 cycles. (C) 2011 Elsevier B. V. All rights reserved.