Heterogeneous photocatalysis has proved to be a useful tool for the degradation of water pollutants over the past 30 years. Despite notable achievements in this domain, a more satisfactory and accurate kinetic model has to be developed further. In this work, to clarify the dependence of the apparent rate constant k(app) of the first-order kinetics on the initial organic content, light intensity and TiO2 content of TiO2/AC (TiO2-coated activated carbon, TA). the photocatalytic treatment of rhodamine B (RhB) as a model compound has been studied by using TA in suspension as a photocatalyst. The photocatalytic degradation kinetic characteristics were experimentally investigated under different reaction conditions (light intensity, initial organic content and TiO2 content of TA). To account for the experimental results, a new kinetic model is proposed on the basis of intrinsic element reactions, which takes into account the effect of light intensity, reaction intermediates, and the absorption performance on h(+) forming, organic compound combining with center dot OH and degradation rate, respectively. The new kinetic model fairly resembles the classic Langmuir-Hinshelwood equation from its expression. However, it does predict that both k(r)(-1) and K-S are linearly proportional to the reciprocal of the square root of the light intensity in a rather large intensity range. The model fits quite well with the experimental data and elucidates phenomena about the effects of the TiO2 content of TA on the degradation rate. (C) 2008 Elsevier B.V. All rights reserved.