The degradation of benzothiazole in aqueous solution by a photo-assisted Fenton reaction has been studied in a batch reactor in the pH range 2.0-3.2 and for H2O2 and Fe(III) concentrations respectively between 1.0 x 10(-3)-1.5 x 10(-1) and 1.0 x 10(-6)-4.0 x 10(-6) M. A kinetic model has been developed to predict the decay of benzothiazole at varying reaction conditions. The use of kinetic constants from the literature in the model allows to simulate the system behavior by taking into account the influence of pH, hydrogen peroxide, Fe(III) and sulfate concentrations and the ionic strength.