Exploring high-performance and stable transition metal electrocatalysts is prerequisite for boosting overall water splitting efficiency. In this study, iron (Fe), manganese (Mn) co-doped three-dimensional (3D) Ni3S2 nanoflowers were in situ assembled by many inter-connected 2D nanosheets on nickel foam (NF) via hydrothermal and sulfuration treatment. By virtue of the introduced Fe and Mn elements and unique flower-like structures, the as-prepared catalyst displayed high activity and stability for oxygen evolution reaction (OER), coupled with a small Tafel slope (63.29 mV dec(-1)) and a low overpotential of 216 mV to reach the current density of 30 mA cm(-2). This study would shed some lights for facile synthesis of exceptional OER catalyst by tailoring the electronic structure and doping transition metal(s). (C) 2020 Elsevier Inc. All rights reserved.