Surface interaction through adsorption and dissociation between H2O and metal oxides plays an important role in many industrial as well as fundamental processes. To gain further insights on the interaction, this study performs dispersion-corrected Hubbard-corrected density functional theory calculations in H2O adsorption and dissociation on stoichiometric and nonstoichiometric CuO(1 1 1) surfaces. The nonstoichiometric surfaces consist of oxygen vacancy defect and oxygen-preadsorbed surfaces. This study finds that H2O is chemically adsorbed on the top of Cusub and Cusub-Cusub bridge due to the interaction of its p orbital with d orbital of Cu. The adsorption is found to be the strongest on the surface with the oxygen vacancy defect, followed by the stoichiometric surface, and the oxygen-preadsorbed surface. The oxygen vacancy increases the reactivity for H2O adsorption and reduces the reaction energy required for H2O dissociation on the surface. However, the surface modification by the oxygen-preadsorbed significantly reduces the barrier energy for H2O dissociation when compared with the other surfaces.