Hydrogen production from electrolyzed water is a mature technology and has great development prospects in terms of energy conversion and utilization. However, the kinetically sluggish oxygen-evolution reaction becomes the limiting step in the electrolysis of water. Copper-based materials have been reported as a good choice to catalyze the oxygen evolution reaction, but their performance is poor. We describe a Cu2-xSe@CuO/copper foam core-shell structure from the in situ electrochemical oxidation of Cu2Se/copper foam to promote the oxygen-evolution reaction performance. The presence of a semi-metallic Cu2-xSe core and nanostructured CuO shell at a current density of 10 mA cm(-2) requires a low overpotential of 253 mV. The Tafel slope was only 73 mV dec(-1). The preparation of Cu2-xSe@CuO on three-dimensional copper foam facilitates the reaction. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.