First-principles calculation on the basis of the density functional theory (DFT) and generalized gradient approximation have been applied to study the adsorption of H-2 on the stoichiometric O-terminated Cu2O (1 1 1), Cu2O (1 1 1)-Cu-CUS and Cu-terminated Cu2O (1 1 1) surfaces. The optimal adsorption position and orientation of H-2 on the stoichiometric O-terminated Cu2O (1 1 1) surface and Cu-terminated Cu2O (1 1 1) surface were determined and electronic structural changes upon adsorption were investigated by calculating the Local Density of States (LDOS) of the Cu-CUS 3d and Cu-CUS 4s of stoichiometric O-terminated Cu2O (1 1 1) surface. These results showed that H-2 molecule adsorption on Cu-CUS site parallel to stoichiometric O-terminated Cu2O (1 1 1) surface and H-2 molecule adsorption on Cu-2 site parallel to Cu-terminated Cu2O (1 1 1) surface were the most favored, respectively. The presence of surface copper vacancy has a little influence on the structures when H-2 molecule adsorbs on Cu-CSA, O-CUS and O-CSA atoms and the H-2 molecule is only very weakly bound to the Cu2O (1 1 1)-Cu-CUS surface. From the analysis of stoichiometric O-terminated Cu2O (1 1 1) Local Density of States, it is observed that Cu-CUS 3d orbital has moved to a lower energy and the sharp band of Cu-CUS 4s is delocalized when compared to that before H-2 molecule adsorption, and overlapped substantially with bands due to adsorbed H-2 molecule. The Mulliken charges of H-2 adsorption on Cu-CUS site showed that H-2 molecule obtained electron from Cu-CUS which was consistent with the calculated electronic structural changes upon H-2 adsorption. (C) 2011 Elsevier B. V. All rights reserved.