Two kinds of metal organic chemical vapor deposition (MOCVD) approaches have been employed for the preparation of the photocatalyst of titanium dioxide supported on alumina. One was simultaneous deposition and calcinations, i.e. a one-step process; the other was preliminary gas impregnation of the support followed by a decomposition step, i.e. a two-step process. The results of characterization indicated that the structure of the support was destroyed by a two-step process because of pore blocking. It was found that the one-step process resulted in a superior photocatalyst: this was attributed to higher external surface concentration and more perfect crystalline structure of TiO2. TiO2/Al2O3 catalysts showed good repeatability. (c) 2004 Elsevier B.V. All rights reserved.