Exposure of acetonitrile/methanol solutions of [PPN][Ru(DPPBT)(3)] [PPN = bis(triphenylphosphoranylidene); DPPBT = 2-diphenylphosphinobenzene thiolate] to oxygen initiates metal-centered oxidation, yielding the ruthenium(III) thiolate Ru(DPPBT)(3). Ru(DPPBT)3 further reacts with oxygen, at sulfur, to give the ruthenium(III) sulfinate complex [Ru(DPPBT-O-2)(2)(DPPBT)], which is reduced under ambient conditions to [PPN][Ru(DPPBT-O-2)2(DPPBT)). Ruthenium(II) sulfinate is the only product isolated from acetonitrile/methanol. Yellow crystals of [PPN][Ru(DPPBT-O-2)2(DPPBT)l were obtained. Ruthenium(III) sulfinate was isolated as green prism-shaped crystals upon oxygenation of [PPN][Ru(DPPBT)31 in chlorobenzene/hexane. Electrochemical oxidation of ruthenium(II) sulfinate yields the ruthenium(III) derivative, which is rapidly reduced back to ruthenium(II) upon the addition of hydroxide.