Unexfoliated graphite oxide (GO) was electrochemically reduced in an alkali solution and the electrochemical oxidative functionalization of electrochemically reduced graphite oxide (ERGO) was achieved by applying a more positive potential than the open circuit potential (OCP) in an alkali solution such as KOH, NaOH or LiOH. Such a method highly increased the specific capacitance of the GO. The electrochemically reduced and functionalized GO exhibited a relatively high cation adsorption capacitance of about 140 F/g. The results indicate that coupled electro-deoxidation/functionalization is a simple, fast and efficient method to improve capacitance, especially the cation adsorption capacitance of reduced GO. (C) 2013 Elsevier Ltd. All rights reserved.