Vanadium pentoxide thin films are prepared via sol-gel spin coating method. The films coated on FTO and glass substrates are treated at different temperatures ranging from 250 degrees C to 400 degrees C. The structural, optical and electrochemical investigations are made. X-ray diffraction analysis shows the film to be composed of V2O5 in beta-phase up to annealing temperature of 350 degrees C and at 400 degrees C the structural transformation to alpha-phase is observed. FTIR spectrum shows the formation of V-O bond. The SEM images reveal the formation of nanopores. Optical absorption studies indicate a band gap of 2.2-2.4 eV. The supercapacitor behaviour is studied using cyclic voltammetery technique and electrochemical impedance analysis. The vanadium pentoxide films annealed at 300 degrees C for an hour exhibits a maximum specific capacitance of 346 F g(-1) at a scan rate of 5 mV s(-1). (C) 2012 Elsevier Ltd. All rights reserved.