Electro-Fenton process for water purification utilizes electrical energy for chemical transformation. However, its key step, oxygen reduction reaction (ORR) to generate H2O2, suffers from added energy consumption due to a side reaction of H-2 evolution. This study attempted to make this process energy effective by using an innovative gas diffusion electrode (GDE) fabricated from a carbon material with highly-ordered pores and large surface area (CMK-3). It was found that the employment of this cathode enabled a low cathodic potential of 0.5 V (vs. SCE), at which H-2 evolution could be greatly eliminated. Meanwhile, the H2O2 built-up at CMK-3 GDE was 3.1 and 4.4 times higher than those at the other two carbon electrodes (graphite GDE and carbon paper). Moreover, dimethyl phthalate (DMP) degradation in the electro-Fenton process using CMK-3 GDE occurred much more rapidly with a reaction apparent rate constant about 8.8 and 11.5 times higher than those using the other two types of electrodes, respectively, whereas the corresponding energy consumption on CMK-3 GDE at the degradation half-life time was only 50% and 27%, respectively. (C) 2012 Published by Elsevier B.V.