Hydrogen energy utilization from water splitting relies on the successful development of earth-abundant, efficient, and stable electrocatalysts for oxygen evolution reaction (OER). Herein, novel cobalt carbonate hydroxide nanorods are synthesized by facile low-temperature precipitation. The nanorods are networked to form mesoporous structure with a large surface area (291.4 m(2) g(-1)) and high pore volume (1.06 cm(3) g(-1)). The obtained catalyst reaches a current density of 10 mA cm(-2) with an overpotential of a 320 mV and a Tafel slope of 39 mV dec(-1). Moreover, OER activity is improved after stability test, while the overpotential drops down to 313 mV. This increase in activity is explained by in-situ conversion from carbonate to hydroxide, resulting in an increase of active sites. The synthesis route allows an efficient way for obtaining novel cobalt-based OER electrocatalyst, and the enhancement in catalytic activity after stability test also gives a new insight for designing high-performance OER electrodes. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.