A cyclometalated dinuclear platinum(II) complex bridged with pyridine-2-thiolate ions, [Pt-2(ppy)(2)(ppy)(2)] (Hppy = 2-phenylpyridine, Hpyt = pyridine-2-thiol) and its oxidized platinum(III) complex, [Pt2Cl2(ppy)(2)(pyt)(2)] have been synthesized and characterized. The divalent complex exhibits intense red luminescence both in solution and in the solid states. Corresponding to the short (PtPt)-Pt-... distance (2.849(1)Angstrom) for [Pt-2(ppy)(2)(pyt)(2)], the reversible conversion between the divalent and trivalent complexes occurs easily with appearance and disappearance of the luminescence.