Transition metal oxides with hierarchical structures that grow on conductive substrates directly, which have been considered as promising catalysts for electrochemical catalysis. In this study, we used a stepwise synthesis method to prepare CuO nanoflake @Co3O4 nanowire composite nano-arrays (denote as CuO/Co3O4 composite), which show an excellent electrochemical performance. In the oxygen evolution reaction (OER), the CuO/Co3O4 composite shows lower overpotential of 450 mV at the current density of 50 mAcm(-2) and a smaller Tafel slope of 42 mV dec(-1) in KOH solution (1 M, pH = 13.7). In the electrocatalytic CO2 reduction reaction, the prepared CuO/Co3O4 composite showed better CO selectivity in KHCO3 aqueous solution (0.1M, CO2 saturated), the corresponding Faradaic efficiency of CO product reached 35.4%, and the product ratio of H-2 to CO was controlled by changing the potential values. The synthesis strategy reported here opens a way for designing high-performance electrodes for electrochemical catalysis and also provides new ideas for the construction of overall reaction (CO2 + H2O -> CO + O-2). (C) 2019 Elsevier Ltd. All rights reserved.