A mathematical model has been developed and applied to simulate the behavior of a chemical reactor for the ozonation of a food-processing secondary wastewater effluent in the presence of granular activated carbon (GAC). The reactor configuration comprises two compartments in series: a bubble column for gas (ozone)-liquid (wastewater) contact and a fixed bed column for solid (catalyst)-liquid (wastewater) reaction. Second order kinetics for both direct ozonation and heterogeneous catalytic zonation has been considered in the kinetic approach. After rate constants determination, the kinetic model was validated by comparing simulated and experimental results at different operating conditions. The mathematical model accurately predicted experimental data and the influence of the studied operating variables in the ozone dose range 0-4 g O-3/g TOC. However, the model failed to predict experimental results when applying higher ozone doses, probably due to the changing nature of the oxidation state of the water matrix. (C) 2011 Elsevier B.V. All rights reserved.