Electrochemical water splitting is a promising technology for mass hydrogen production. Efficient, stable, and cheap electrocatalysts are keys to realizing this strategy. However, high price and preciousness of commonly used noble metal based catalysts severely hinder this realization. Herein, we report nickel iron phosphide (Ni-FexP) bifunctional electrocatalyst via the in-situ growth of Ni-Fe(OH)(x) on nickel foam (Ni-Fe(OH)(x)/NF) followed by low-temperature phosphidation. As a hydrogen evolution reaction (HER) catalyst, the Ni-FexP/NF only needs an overpotential of 119 mV to drive a current density of -10 mA/cm(2) in a base media. It also shows excellent activity toward oxygen evolution reaction (OER) with low overpotentials of 254 mV, 267 mV, and 282 mV at 50, 100 and 200 mA/cm(2), respectively. Moreover, when this bifunctional catalyst is used for overall water splitting, a low cell voltage of 1.62 V is needed to deliver a current density of 10 mA/cm(2), which is superior to commercial electrolyzes and it also shows remarkable stability. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.