The growth of titania nanoparticles within the mesopores of SBA-15 has been controlled by a post-synthesis deposition using the acid-catalyzed sol-gel method (ACSG). The crystal size, the location and the crystalline phase of the titania nanoparticles can be tuned by a careful adjustment of the preparation conditions. The influence of the initial titania amount, the pH and the temperature on the characteristics of titania-SBA-15 catalyst has been studied. The combined data from the structural and chemical analysis demonstrates that titania nanoparticles with different sizes were grafted within the SBA-15 channels. The formation mechanism of the titania nanoparticles within the mesopores is discussed. The photodecomposition of rhodamine 6G (R6G) in aqueous medium was selected as probe reaction to test the photoactivity of the titania-SBA-15 powders and to verify the potential use of these materials for wastewater treatment. It was shown that the preparation method and the structural characteristics of the mesoporous materials are of great importance for the adsorption capacity and the photocatalytic activity. (C) 2006 Elsevier B.V. All rights reserved.