The present work describes the preparation and electrochemical characterisation of titanium/iridium(IV) oxide: tantalum pentoxide (Ti/IrO2:Ta2O5) electrodes for vanadium redox flow battery applications. The electrode surface morphology is examined by field-emission scanning electron microscopy, and their electrochemical behaviours are studied by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. A charge-discharge study has been performed at different current densities using vanadium sulphate as an electrolyte medium (1.7 M V3.5+ and 4 M H2SO4), and as-prepared Ti/IrO2:Ta2O5 and pristine graphite are used as the anode and cathode, respectively. To better understand the behaviour of the electrodes and for comparison, a vanadium redox flow battery is also constructed using graphite as the anode as well as the cathode, and its charge-discharge performance is examined. The electrochemical study revealed that the Ti/IrO2:Ta2O5 electrodes exhibit slightly higher catalytic activity and long-term stability than the graphite electrode in highly concentrated sulphuric acid medium. The Ti/IrO2:Ta2O5 electrodes also exhibit slightly higher energy density (33 Wh L-1) than the graphite electrode (31.5 Wh L-1). However, the energy efficiency of Ti/IrO2:Ta2O5 electrode at 40 mA cm(-2) is 81%, which is lower than that of the graphite electrode (86% at 40 mA cm(-2)). (C) 2013 Elsevier B.V. All rights reserved.