The surface redox activities, the oxygen evolution reaction (OER), the oxidation of formic acid (FA) and the anodic stability have been investigated and compared on IrO2 electrodes prepared by two techniques: the thermal decomposition of H2IrCl6 precursor (TDIROF) and the thermal treatment of metallic iridium (TOIROF). It was found, that the surface redox activities involved on both IrO2-based electrodes are similar. Concerning the oxygen evolution reaction and the oxidation of formic acid, both films show similar mechanism.