A special kind of photocatalysis-a photosensitized oxidation involving singlet molecular oxygen (O-1(2)) was applied to decomposition of 2-chlorophenol (2-CP) in water solution. The photoprocess was carried out in a homo- and heterogeneous system using rose bengal (RB) as a sensitizer. In the homogeneous solution the influence of initial 2-CP concentration and pH on reaction rate was observed. Based on the kinetic model, the rate constants Of O-1(2) quenching and reaction with 2-CP and the rate constant of excited sensitizer quenching by 2-CP were determined. In the heterogeneous system, silane gel was a carrier for the immobilized sensitizer. In order to estimate kinetic parameters, an attempt was made to describe the process using Langmuir-Hinshelwood (L-H) type mechanism. The Langmuir equilibrium constants for oxygen and 2-CP adsorbed on the gel surface were also estimated. (c) 2007 Elsevier B.V. All rights reserved.