In this paper, NiO/TiO2 nanotube composites were synthesized by loading various amounts of NiO on TiO2 nanotubes. The electrochemical capacitance performance of this composite was investigated by cyclic voltammgoram, ac impedance, and galvanostatic charge-discharge tests with a three-electrode system in 1 mol/L KOH solution. The results of these tests prove that the three-dimensional nanotube network of TiO2 offers a solid support structure for the active materials NiO, allows the active material to be readily accessible for electrochemical reactions, and improves the efficiency of the active materials. For this reason, the TiO2 nanotubes used as a support for NiO enhance the utilization of NiO greatly. A maximum specific capacitance of 550 F/g was obtained for the NiO loaded on the TiO2 nanotubes. (c) 2005 The Electrochemical Society. All rights reserved.