Utilities of hybrid photocatalyst consisting of TiO2 and an adsorbent such as activated carbon in photoinduced mineralization of organic substances of very dilute present concentrations are demonstrated for the photodecomposition of propionaldehyde in air atmosphere. and propyzamide and bromoform dissolved in water. The substrates of target were adsorbed on the adsorbent support, and then a high concentration environments of the substrate was formed around the loaded TiO2, resulting in an increase in the photodestruction rare. Evidences for the diffusion of propionaldeyde adsorbed on the mordenite support to the loaded TiO2 are presented. Merits of the use of the adsorbents as the support for TiO2 loading is discussed. (C) 2000 Elsevier Science B.V. All rights reserved.