Designing cost-efficient and durable electrocatalysts toward oxygen evolution reaction (OER) has been of vital significance for the commercial development of various renewable energy systems. Herein, we report the construction of a new class of 3D hollow nanoflower catalysts that assembled by ultrathin nickel-molybdenum phosphide nanosheets. Owing to the increased electronic and ion transport channels, the heteroatom doping, and synergistic effects from the interconnected compositions, the newly-generated 3D MoNiP hollow nanoflowers display superior OER activity than that of Ir/C. And the optimized Mo1Ni1P hollow nanoflowers (Mo1Ni1P HNFs) can afford a current density of 10 mA cm(-2) at the overpotential of 275 mV in 1.0 M KOH solution. More importantly, the resultant Mo1Ni1P HNFs also display excellent stability with negligible activity and morphology decay. This work provides insights for the utilization of earth-abundant and highly efficient electrocatalysts via rationally designing the morphology of electrocatalysts. (C) 2018 Elsevier Inc. All rights reserved.