A series of sulfido-bridged tungsten -ruthenium dinuclear complexes CP*W(mu-S)(3)RuX(PPh3)(2) (4a; X = Cl, 4b; X = H), CP*W(O)(mu-S)(2)RuX(PPh3)(2) (5a; X = Cl, 5b; X = H), and Cp*W(NPh)(mu-S)(2)RuX(PPh3)(2) (6a; X = Cl, 6b; X = H) have been synthesized by the reactions of (PPh4)[Cp*W(S)(3)] (1), (PPh4)-[CP*W(O)(S)(2)] (2), and (PPh4)[Cp*W(NPh)(S)(2)] (3), with RuClX(PPh3)(3) (X = Cl, H). The heterolytic cleavage of H-2 was found to proceed at room temperature upon treating 5a and 6a with NaBAr4F (Ar-F = 3, 5-C6H3-(CF3)(2)) under atmospheric pressure of H2, which gave rise to [Cp*W(OH)(mu-S)(2)RuH(PPh3)(2)](BAr4F) (7a) and [Cp*W(NHPh)(mu-S)(2)RuH(PPh3)(2)](BAr4F) (8), respectively. When CP*W(O)(mu-S)(2)Ru(PPh3)(2)H (5b) was treated with a Bronstead acid, [H(OEt2)(2)](BAr4F) or HOTf, protonation occurred exclusively at the terminal oxide to give [Cp*W(OH)(mu-S)(2)RuH(PPh3)(2)](X) (7a; X = BAr4F, 7b; X = OTf), while the hydride remained intact. The analogous reaction Of CP*W(mu-S)(3)Ru(PPh3)(2)H (4b) led to immediate evolution of H-2. Selective deprotonation of the hydroxyl group of 7a or 7b was induced by NEt3 and 4b, generating Cp*W(O)(mu-S)(2)RU(PPh3)(2)H (5b). Evolution of H2 was also observed for the reactions of 7a or 7b with CH3CN to give [CP*W(O)(mu-S)(2)Ru(CH3CN)(PPh3)(2)](X) (11a; X = BAr4F, 11b; X = OTf). We examined the H/D exchange reactions of 4b, 5b, and 7a with D-2 and CH3OD, and found that facile H/D scrambling over the W-OH and Ru-H sites occurred for 7a. Based on these experimental results, the mechanism of the heterolytic H-2 activation and the reverse H-2 evolution reactions are discussed.