Reactions of tin porphyrins with vicinal diols were investigated. Treatment of (TTP)Sn(Cequivalent toCPh)(2) or (TTP)Sn(NHtolyl)(2) with pinacol and 2,3-diphenylbutane-2,3-diol afforded diolato complexes (TTP)Sn[OC(Me)(2)C(Me)(2)O] (1) and (TTP)Sn[OC(Ph)(Me)C(Ph)(Me)O] (2), respectively. Both complexes underwent C-C cleavage reactions to give (TTP)Sn-II and ketones. Reaction of (TTP)Sn(Cequivalent toCPh)(2) with 1 equivalent of o-catechol generated (TTP)Sn(Cequivalent toCph)(OC6H4OH) (3), which subsequently transformed into (TTP)Sn(OC6H4O) (4). With excess catechol, disubstituted (TTP)Sn(OC6H4OH)(2) (5) was obtained. (TTP)Sn(Cequivalent toCPh)(OCHRCHROH) (R = H, 6; R = Ph, 8) and (TTP)Sn(OCHRCHROH)2 (R = H, 7; R = Ph, 9) were obtained analogously by treatment of (TTP)Sn(Cequivalent toCPh)(2) with appropriate diols. In the presence of dioxygen, tin porphyrin complexes were found to promote the oxidative cleavage of vicinal diols and the oxidation of alpha-ketols to alpha-diketones. Possible reaction mechanisms involving diolato or enediolato intermediates are discussed. The molecular structure of (TTP)Sn(Cequivalent toCPh)(OC6H4OH) (3) was determined by X-ray crystallography.