Solar degradation of effluents of pulp mill industry containing toxic chemicals has been studied using TiO2/Fe(III) (Degussa P25 TiO2 was used as a catalyst). Effects of some operating parameters such as the initial oxidant and catalyst concentrations and circulation rates of wastewater on TOC, color and AOX removals were investigated using the Box-Wilson statistical experimental design method. The highest color, TOC and AOX removals of 78%, 64% and 68% were obtained at TiO2 concentration of 188 mg/L and Fe (III) concentration of 0.5 mM, respectively. (C) 2010 Elsevier B.V. All rights reserved.