In electrochemistry, IrO2 exhibits both high catalytic activity and excellent catalytic stability for the oxygen evolution reaction (OER). Here, IrO2 electrocatalyst are prepared by Adams method and the effect of the calcination temperature, the content of NaNO3 and solvent on the properties of IrO2 electrocatalysts are investigated. The best synthesis conditions for IrO2 are: a calcination temperature of 550 degrees C, a mass ratio of H2IrCl6 center dot 6H(2)O to NaNO3 of 1:20 and using water as the solvent. The resulting IrO2 electrocatalyst shows a high crystallinity of 90%, a specific surface area of 126.4 m(2) g(-1) and a high OER activity of 90 mA cm(-2) at 1.5 V. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.