Electrochemical water splitting is considered to be one of the most promising strategies for clean and efficient hydrogen production. In this paper, an in-situ growth of iron-nickel phosphide on nickel foam (FeNiPx/NF) is demonstrated as a self-supported ternary catalyst for electrochemical water splitting. The FeNiPx/NF were prepared by a thermo-reaction between NaH2PO2 and NiFe hydroxide precursors that are in situ grown on Ni foam via a simple chemical precipitation reaction. In this newly proposed method, the nickel foam not only acts as an electrode substrate, but also serves as a slow-release Ni source in the reaction due to its oxidation by Fe3+ in solution. Benefiting from collaborative advantages of bimetallic composite, metallic phosphide, and unique electrode fabrication, the FeNiPx/NF exhibits extraordinarily high activities for both OER and HER with low overpotentials of of 192 and 106 mV at 10 mA cm(-2), 236 and 161 mV at 100 mA cm(-2), respectively. The voltage during the galvanostatic electrolysis is well maintained for almost 400 h without any visible elevation, representing the few most stable noble-metal-free catalysts for water splitting. (C) 2017 Elsevier Ltd. All rights reserved.