The synthesis of 7-oxy-3-(3,4,5-trimethoxyphenyl)coumarin tetra-substituted indium(III) phthalocyanine complexes have been performed for the first time in this study. The new compounds were characterized by IR, H-1 NMR, electronic spectroscopy and mass spectra. The photochemical properties such as singlet oxygen generation and photostability were investigated in dimethylsulfoxide (DMSO) solutions. The effects of the positions (peripheral or non-peripheral) of substituents on the phthalocyanine framework and variety (chlorine or acetate) of axial groups on the central indium(III) metal ion on these properties were also compared in this study. (C) 2014 Elsevier B.V. All rights reserved.