The photocatalytic degradation kinetics of rhodamine B (RhB) by TiO2-coated activated carbon (TiO2/AC) catalyst under different reaction conditions (light intensity, TiO2 content in TiO2/AC and initial content of contamination) was elucidated by modeling. The kinetics of Rhb photodegradation was found to follow the first-order rate law and could be described in terms of a modified Langmuir-Hinshelwood model. The value of the apparent rate constant k(app) was proposed on the basis of intrinsic element reactions, such as light intensity, reaction intermediates and the photo-induced hole (h(+/-)) formation. The apparent rate constant k(app) first increased with increasing TiO2 content of the TiO2/AC catalyst and then decreased. The optimal value of the TiO2 content could be obtained through the model; the apparent rate constant was linear with respect to the square of the intensity. The validity of the model was also proved with other researchers' results. (C) 2010 Elsevier B.V. All rights reserved.