The dehydrogenation reaction of H2S by the 3∑- ground state of VS+: VS+ + H2S → VS2+ + H2 has been studied by using Density Functional Theory (DFT) at the B3LYP/DZVP level. It is found that the reaction proceeds along two possible pathways (A and B) yielding two isomer dehydrogenation products VS2+-1 (3B2) and VS2+-2 (3A1), respectively. For both pathways, the reaction has a two-step-reaction mechanism that involves the migration of two hydrogen atoms from S2 to V+, respectively. The migration of the second hydrogen via TS3 and that of the first via TS4 are the rate-determining steps for pathways A and B, respectively. The activation energy is 17.4 kcal/mol for pathway A and 22.8 kcal/mol for pathway B relative to the reactants. The calculated reaction heat of 9.9 kcal/mol indicates the endothermicity of pathway A and that of –11.9 kcal/mol suggests the exothermicity of pathway B. The dehydrogenation reaction of H2S by the 3Σ-ground state of VS +: VS + + H2S → VS2 + + H2 has been studied by using Density Functional Theory (DFT) at the B3LYP / DZVP level. It is found that the reaction proceeds along two possible pathways (A and B) yielding two isomer dehydrogenation products VS2 + -1 (3B2) and VS2 + -2 (3A1), respectively. For both pathways, the reaction has a two-step-reaction mechanism that involves the migration of two hydrogen atoms from The migration of the second hydrogen via TS3 and that of the first via TS4 are the rate-determining steps for pathways A and B, respectively. The activation energy is 17.4 kcal / mol for pathway A and 22.8 kcal / mol for pathway B relative to the reactants. The calculated reaction heat of 9.9 kcal / mol indicates the endothermic of pathway A and that of -11.9 kcal / mol suggests the exothermicity of pathway B.