CuO nanobelts have been successfully prepared with high yield via a simple hydrothermal reduction process at a low temperature. The as-prepared CuO nanowires were characterized by XRD, SEM, TEM and HRTEM techniques. The growth mechanism of these nanostructures is discussed. The electrochemical tests show that the ultrafine CuO nanobelts, as a promising electrode material, can deliver a large discharge capacity of about 500 mA h g(-1). (C) 2008 Elsevier B.V. All rights reserved.