The adsorption and dissociation mechanisms of H₂S on a TiO₂ (001) surface were elucidated using first principles calculation based on the density functional theory. The interaction of the intermediates involving S, HS and OH species has been discussed in detail. For these species, the most favorable adsorption sites were determined and led to further computations involving dissociation of H₂S into HS and H and bonding of H-atom with the OH to form water on the surface. The creation of vacancies along with the presence of S on the surface enhanced the H₂S adsorption energy slightly. However, addition of OH in the system caused H₂S to bind on the surface sufficiently strongly. Additionally, H₂S decomposition was found to be a spontaneous process in the presence of OH radicals.