In this study, the decoloration of toludine blue (TB) in the presence of UV radiation and heterogeneous hybrid catalyst, namely titanium oxide impregnated with vanadium oxide was optimized using response surface methodology (RSM). The optimum removal conditions were determined as 26.5 mg/20 mL V2O5/TiO2 catalyst concentration at pH 7.7. At optimized conditions the complete decoloration was obtained at 50 mu M TB concentration. In the optimization, R-2 and R-adj(2) Correlation coefficients for quadratic model was evaluated quite satisfactorily as 0.98 and 0.96, respectively. (C) 2007 Elsevier B.V. All rights reserved.