The efficiency of water splitting is restricted by the slow kinetics of oxygen evolution reaction (OER) for large scale hydrogen production. Designing highly efficient, low-cost and long-lasting catalysts for OER is being actively pursued. In order to improve the catalytic activity of nickel-iron hydroxide (NiFe) for OER, MoO42- as a promoter is doped into NiFe. We reported a porous amorphous MoO42--doped nickel-iron hydroxide (NiFeMo) composite on nickel foam (NF) via a facile electrodeposition method. The as-prepared NiFeMo/NF electrode displays a highly efficient catalytic activity for OER in alkaline solution and delivers a current density of 20 mA cm(-2) with an overpotential merely of 230 mV in 1.0M KOH. The catalyst also exhibits extraordinary performance at high current densities and is comparable to the some Ni-based OER electrocatalysts reported to date. The high active surface areas, high surface wettability and the low charge-transfer resistance of NiFeMo/NF catalysts by a doping of MoO42-, together with effective mass transport offered by the hierarchical 3D macroporous structure, all contribute to the extraordinary synergistic OER performance. (c) 2017 Elsevier Ltd. All rights reserved.