This paper aimed to reveal the removal effectiveness and the mechanism of catalytic ozonation in the presence of aluminum oxides (gamma-AlOOH, gamma-Al2O3, and alpha-Al2O3) for the degradation of a taste and odor compound. Results showed that catalytic ozonation in the presence of aluminum oxides can substantially enhance 2,4,6-trichloroanisole (TCA) removal compared with the sole ozonation. However, three kinds of aluminum oxides exhibited different catalytic activity in catalytic ozonation for the degradation of TCA remarkably. Scavenging experiments of hydroxyl radicals revealed that the improving removal effectiveness of TCA was due to the enhancing generation of hydroxyl radicals. The catalytic activity of the aluminum oxides was related to highly hydroxylated surface. The surface hydroxyl groups on the aluminum oxides were active sites in catalytic ozonation. The density of surface hydroxyl groups and the surface Bronsted acidity determined the difference of the catalytic activity of aluminum oxides. The higher density of surface hydroxyl groups and the stronger Bronsted acidity of the surface can remarkably enhance the catalytic activity. (C) 2009 Elsevier B.V. All rights reserved.