The decolorization and mineralization of Acid Red 27 (AR27), an anionic monoazo dye of acid class, were studied by UV/H202 process in laboratory and real samples. Effects of different process parameters such as initial H2O2 and AR27 concentrations, pH and EtOH as an electron scavenger have been studied. H2O2 and UV light have a negligible effect when they were used on their own. The decolorization rate follows pseudo-first order kinetic with respect to the dye concentration. The rate constant of the attack of *OH radicals to the AR27 has been estimated through the adoption of a simplified kinetic model (1.03 x 10(8)M(-1)s(-1)). This model allows predicting the pseudo-first order rate constant and concentration of AR27 in different illumination times for different initial concentrations of H2O2. Mineralization studies showed, the formation of sulfate ions, the decrease of pH and 85% of COD reduction occur in less than 60 min. In the real wastewater color removal could be achieved after only 75 min, whereas 45% of COD reduction occurs after 105 min of illumination.