A facile one-step route has been developed to electrodeposite P-Co nanoparticles on a nickel foam in deep eutectic solvents. The as-prepared catalyst exhibits excellent performance towards both hydrogen evolution reaction and oxygen evolution reaction. Only 62 mV and 320 mV overpotentials were required to reach a current density of 10 mA cm(-2) for hydrogen evolution reaction and oxygen evolution reaction, respectively. That current density is measured at the voltage of 1.59 V for an overall water splitting when used as both anode and cathode. The scanning electron microscopy images indicate a high dispersion of the P-Co sample on the Ni foam. The prepared material possesses a relative high ECSA and a low charge transfer resistance, indicating a large number of active sites for water splitting. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.