Vanadium pentoxide/reduced graphene oxide (V2O5/rGO) nanocomposite film was fabricated by a facial sol-gel method. X-ray diffraction demonstrated that the interlayer distance of V2O5 increased from 1.05 to 1.36 nm due to the introduction of rGO. Raman spectra confirmed the co-existence of V2O5 and rGO in the V2O5/rGO nanocomposite film. Scanning electron microscopy revealed that V2O5 nanoparticles were well distributed on the surfaces of rGO sheets. And cyclic voltammograms and in-situ optical transmittance measurements confirmed that the V2O5/rGO composite film had better cyclic stability, faster switching speed, larger optical modulatory range and higher coloration efficiency compared with the V2O5 film. Moreover, the electrochemical impedance spectroscopy revealed that the V2O5/rGO composite film evinced the lower resistance due to the good interaction between the rGO sheets and the V2O5 nanoparticles. These improvements can be ascribed to the synergistic effect of rGO sheets and V2O5 nanoparticles. This study would be significant for optimizing the electrochromic performances of other transition metal oxide electrochromic materials by the incorporation of rGO. (C) 2016 The Electrochemical Society. All rights reserved.