Alkaline oxygen evolution reaction (OER) electrocatalysts have been widely studied for improving the efficiencyand green hydrogen production through electrochemical water splitting. Transition metal-based electrocatalysts have emergedas promising materials that can significantly reduce the hydrogen production costs. Among the available electrocatalysts,transition metal-based layered double hydroxides (LDHs) have demonstrated outstanding OER performance owing to theabundant active sites and favorable adsorption-desorption energies for OER intermediates. Currently, cobalt doped nickel LDHs(NiCo LDHs) are regarded as the benchmark electrocatalyst for alkaline OER, primarily owing to the physicochemicalsynergetic effects between Ni and Co. We report effects of heat-treatment of the as-grown NiCo LDH on electrocatalyticactivities in a temperature range from 250 to 400°C. Electrocatalytic OER properties were analysed by linear sweep voltammetry(LSV) and electrochemical impedance spectroscopy (EIS). The heat-treatment temperature was found to play a crucial rolein catalytic activity. The optimum heat-treatment temperature was discussed with respect to their OER performance.