The photosensitizing properties of various water-soluble zinc and aluminum phthalocyanines towards the phototransformation of 4-chlorophenol (4-Cp) are presented. The complexes studied are the zinc (ZnPcS 4 ) and aluminum (AlPcS 4 ) tetra-sulfophthalocyanines; the zinc and aluminum complexes containing a mixture of differently substituted sulfophthalocyanines (represented as zinc (ZnPcS m i x ) and aluminum (AlPcS m i x ), respectively); the zinc (ZnOCPc) and aluminum (AlOCPc) octacarboxy phthalocyanines. The AlPcS m i x and ZnPcS m i x complexes showed the best photocatalytic activity towards the transformation of 4-Cp. The values of singlet oxygen quantum yields of the sensitizers were obtained, and it was found that the rates of 4-Cp photooxidation, in general, follow the efficiency of singlet oxygen photosensitization by the phthalocyanine complexes. At 4-Cp concentration below 10 - 4 moll - 1 , photooxidation by singlet oxygen is the dominating mechanism of substrate photodegradation, while at 4-Cp concentration above 10 - 3 moll - 1 the role of Type I mechanism increases. Kinetic analysis indicates that interaction of 4-Cp with singlet oxygen mainly results in ''physical'' quenching with (k q +k r )=(13.5+/-3)x10 8 mol - 1 ls - 1 and k r =(2.7+/-0.3)x10 8 mol - 1 ls - 1 for the phenolate form of 4-Cp, which significantly limits the rates and quantum yields of 4-Cp photooxidation.