Display omitted •Rapid low-temperature synthesis of hollow CuS0.55 nanoparticles has been shown.•The hollow nanostructure greatly improves electrochemically active surface area.•The rich Cu sites show strong adsorption ability to targeted OOH∗ intermediates.•An ultralow overpotential is required for water oxidation in alkaline media. Developing low-cost and binder-free Cu-based electrocatalysts for high-performance oxygen evolution reactions (OER) is of great importance to promote their practical applications. Herein, we demonstrate the low-temperature and rapid synthesis of hollow CuS0.55 nanoparticles on a Cu foam as highly active OER electrocatalysts through an anodic oxidation electrodeposition technique. The large electrochemically active surface area and strong adsorption ability of Cu sites to targeted OOH∗ intermediates are beneficial for enhancing catalytic properties. As a consequence, the hollow CuS0.55 nanoparticles exhibit an ultralow overpotential of 386 mV to achieve a high current density of 100 mA cm−2 in alkaline media with a very small Tafel slope of 33 mV dec−1, which is among the best reported for Cu-based electrocatalysts. The turnover frequency (TOF) is approximately 6 times higher than those of the corresponding CuS0.57 and CuO catalysts. This work provides a simple and feasible approach that can be scaled up easily to construct low-cost and efficient Cu-based OER electrocatalysts.