Irradiating the cyclometalated pincer complex Pt-II(DPA)Cl (1, DPA = 1,8-bis(diphenylphosphino)anthracene) in the presence of O-2 led to three sequential oxidations of the anthracenyl ring. The first photoproduct, a Pt-II-9, 10-endoperoxide complex, was converted photochemically to a Pt-II-9-hydroxyanthrone complex A which was further oxygenated to a Pt-II-hemiketal (B). The oxidation of A, which could be accelerated by light irradiation, Probably involved a Pt-II-anthraquinone intermediate. B underwent acid-catalyzed ketalization to form a binuclear Pt-2(II)-diketal (B1). The photolysis was followed by UV-vis absorption and NMR spectroscopy, and the structures of A and B1 were characterized by single crystal X-ray diffraction.