The aim of this Study is to obtain optimal decolourization conditions for acid blue-7 (AB7) wastewater treatment by Ti/TiO2 photoelectrocatalysis using response surface methodology (RSM). On the basis of a three-variable Box-Behnken design (BBD), RSM was used to determine the effect of pH values (range 3.2-6), light intensity (range 10-20 x 10(2) mu W/cm(2)) and bias potential (range 0.1-1.1 V) on the levels of response, i.e. decolourization efficiency. By applying the quadratic regression analysis, the equations describing the behaviors of the response as simultaneous functions of the selected independent variables were developed. Accordingly, the optimal conditions were determined as pH of 3.41, light intensity of 16.02 x 10(2) mu W/cm(2) and bias potential of 0.68 V. Decolourization efficiency of 90.13%, obtained experimentally under such optimal conditions, agreed was highly with that of 90.44%, estimated by the equations.