The influence of IrO2 loading on the effectiveness factor Et of the electrochemical oxidation of isopropanol was investigated A model has been proposed based on three main reactions electrochemical IrO2 oxidation to IrO3 chemical oxidation of the organic compound via IrO3 and O-2 evolution via decomposition of IrO3 It has been found that the relative effectiveness factor E-f for the electrochemical oxidation of IrO2 to IrO3 is loading independent contrary to the chemical reaction which decreases with increasing IrO2 loading (C) 2010 Elsevier Ltd All rights reserved