The photocatalytic degradation of hazardous dye guillotine yellow, employing a heterogeneous photocatalytic process using TiO2 photocatalyst irradiated with 6W UV light source tungsten lamp, has been studied. The effect of various operational parameters, i.e., dye concentration, photocatalyst concentration, pH of the solution, substrate concentration, and electron acceptor such as hydrogen peroxide on the degradation rate of aqueous solutions of quinoline yellow has been examined. The disappearance of the dye follows a pseudo first order kinetics according to the Langmuir Hinshelwood model. Results show that the use of an efficient photocatalyst and the selection of optimal operational parameters may lead to complete decolorization and to sustainable decrease in the chemical oxygen demand (COD) of the dye waste water. (C) 2011 Elsevier Inc. All rights reserved.