The dicationic Os(II) complex [Os(bpy)(PPh(3))(2)(CO)(H-2)](2+) has been prepared as the triflate salt. The presence of a bound dihydrogen ligand is indicated by a short T-1 minimum value consistent with an H-H distance of 1.05 Angstrom. In the partially deuterated derivative J(HD) = 25.5 Hz was observed. By comparison to other structurally characterized complexes, the observed H-D coupling is most consistent with a II-II distance greater than 1 Angstrom, which requires that the bound H-2 ligand be in the slow rotation regime. The dicationic complex is a strong acid, indicating that the bound H-2 is substantially activated toward heterolytic cleavage. The H-2 ligand is tightly bound to the metal center, and does not undergo exchange with D-2 over the course of several weeks at room temperature. A related dicationic Os(II) complex, [Os(bpy)(2)(CO)(H-2)](2+), has also been prepared. A short T-1 minimum value and a J(HD) value of 29.0 Hz in the partially deuterated derivative is most consistent with a H-H distance of 0.99 Angstrom. The bound H-2 ligand of this complex is significantly less activated toward heterolytic cleavage and is stable in solution for less than a day at room temperature.