TiO2 nanotube arrays are modified by a facile cathodic reduction process treatment and the results are discussed in terms of their electrochemical activity and conductivity. The instrumental characterizations such as X-ray photoelectron spectroscopy and Raman spectroscopy indicate that the formation of oxygen vacancies in the lattice and introduction of hydroxyl groups on the surface of TiO2 take place. The capacitance of the modified sample is found to be 13 times larger than the pristine TiO2 nanotube arrays. This work reveals a feasible and simple method to improve electrochemical activity and conductivity of TiO2 for supercapacitors application. (C) 2013 Elsevier B.V. All rights reserved.