In this study, the successful decolorization and mineralization of phthalocyanine dye (C.I. Direct Blue 199, DB 199) by an advanced oxidation process (AOP), UV/H2O2, were observed while the experimental variables such as hydrogen peroxide dosage, UV dosage, initial dye concentration and pH were evaluated. The operating conditions for 90% decolorization of C.I. DB 199 and 74% removal of total organic carbon (TOC) were obtained for initial dye concentration of 20mg 1(-1), hydrogen peroxide dosage of 116.32 mM, UV dosage of 560W and pH of 8.9 in 30 min. The pseudo-first order rate constant is a linear function of reverse of initial dye concentration. They linearly increased by incrementing UV dosage, yet were non-linear enhancement by increasing the hydrogen peroxide concentration. A higher pseudo-first order rate constant about 0.15 min(-1) was observed while hydrogen peroxide concentration within 5.82-116.32 mM. Moreover, the decolorization of C.I. DB 199 was observed to be more difficult than that of an azo dye, C.I. Acid Black 1, under the same operating conditions. (c) 2005 Elsevier B.V. All rights reserved.