Visible light detoxification of methyl orange (MO) was achieved with a photo-stable 2,9,16,23-tetracarboxyl phthalocyanine (TcPc)/amorphous TiO2, hybrid photocatalyst. TcPc/amorphous TiO2 exhibits an excellent photocatalytic activity under visible irradiation (lambda > 550 nm). Besides the active oxygen species, sensitizer radical cation, TcPc+, was also found to react with MO directly and induce the photodegradation of MO significantly for the first time in dye sensitized photocatalytic system. (c) 2005 Elsevier B.V. All rights reserved.