The protocol to intrinsically achieve efficient oxygen evolution reaction is to maximize the catalytic activity by regulating the micro/nanostructures of electrocatalysts. Herein, we demonstrate the construction of the CoS2 nanosheets assembled three-dimensional hierarchical microboxes by a facile solvothermal process and subsequent sulfurization, where the porous building blocks are cross-linked by numerous nanoparticles. Such attractive nanostructures facilitate sufficient exposure of electrocatalytic active sites with rapid ions transfer. The as-obtained CoS2 microboxes exhibit excellent oxygen evolution reaction electrocatalytic performance with a small overpotential of only 308 mV in 1.0 mol L-1 KOH solution to achieve a current density of 10 mAcm(-2), which is much lower than the CoS2 nanoparticles (336 mV) and the CoS2 nanosheets aggregations (339mV). The Tafel slope is as low as 41.4mV dec(-1). Furthermore, they also show a negligible overpotential change during 8 h chronopotentiometry measurement. This present work highlights the importance of micro/nanostructure design for improving oxygen evolution reaction performance of water oxidation electrocatalysts. (C) 2018 Elsevier Ltd. All rights reserved.