The design of efficient and low-cost electrocatalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remains a significant challenge for the hydrogen production. Herein, CuO nanowires encapsulated by Ni and NiFe hydroxides (CuO@Ni/NiFe hydroxides) in-situ grown on the surface of Cu plate were fabricated via chemical oxidation-calcination process and room-temperature interfacial Galvanic reaction, which were applied to the efficient overall water splitting. Thanks to the improved specific surface area and the conductivity, the optimized core-shell CuO@Ni/NiFe hydroxides nanowire array exhibit impressive OER performance as well as HER activity in 1 M KOH which delivers a current density of 10 mA cm(-2) at an overpotential of 230 mV for OER and 125 mV for HER. Significantly, core-shell CuO@Ni/NiFe hydroxides used as bifunctional catalysts for an overall water splitting can achieve a low onset potential of similar to 1.50 V and a relatively high specific current density of 40 mA cm(-2) at similar to 1.73 V. This feasible strategy provides an accumulative opportunity for fabricating low-cost, effective bifunctional catalysts for overall water splitting. (C) 2019 Elsevier Ltd. All rights reserved.