Cu2O octahedral microcrystals were prepared on the ITO glass by galvanostatic electrodeposition in CuSO4 solution with poly(vinylpryrrolidone) as the surfactant. By controlling the electrodeposition time, the microcrystals could be randomly distributed on the ITO glass and separated from each other, resulting in as many as possible (1 1 1} crystalline planes were exposed. Such microcrystals immobilized on ITO glass were employed in photodegradation of dye pollutants in the presence of H2O2 under a 150 W halogen tungsten lamp. The photodegradation of methylene blue was taken as an example to evaluate the photocatalytic activities of the octahedral Cu2O microcrystals. Effects of electrodeposition time and H2O2 amount on the degradation efficiency was discussed, giving the optimum conditions and the corresponding degradation mechanism. The catalyst showed high ability in degradation of methylene blue, methyl orange, rhodamine B, eosin B. and their mixtures under identical conditions. (C) 2013 Elsevier Ltd. All rights reserved.