The photocatalytic oxidation of atrazine was studied. The time-dependent concentration profiles were measured under different experimental working conditions in a laboratory plant. All experiments were carried out using immobilized TiO2 and a reactor design adapted to solar application. Not only influence on the rate of degradation of the initial pollutant concentration and UV irradiation but also that on mass fluid flow was studied. Whatever the conditions, profiles were successfully modeled thanks to a coupling that involves mass transfer limitation between the fluid and the photocatalytic media and the degradation reaction happening for the adsorbed pollutant. The mathematical model suggested can readily be applied to reactor design and scale-up. (C) 2008 Elsevier B.V. All rights reserved.