Understanding the impact of CuO in selective catalytic reduction (SCR) process for elemental mercury removal will broaden the applicability of SCR system in Hg removal strategies. First principles quantum mechanical methods based on density functional theory were used to investigate the adsorption mechanism of Hg on CuO (110) surface. The CuO (110) surface was represented by a periodic model, and different adsorption sites were considered. The electronic structural changes upon adsorption were also studied to better understand the surface reactivity. The results show that elemental mercury binds weakly to the O-terminated CuO (110) surface, which indicates a physisorption mechanism. On the contrary, Hg is strongly adsorbed on the Cu-terminated CuO (110) surface and chemisorption is the likely adsorption mechanism. The adsorption of Hg on CuO (110) surface is mainly by the Cu-terminated mode. Cu-sub top is the most advantageous adsorption site with an adsorption energy of -116.76 kJ/mol. In addition, bond population analysis indicates that Hg atom preferably adsorbs on CuO (110) surface with the bonding of Cu atoms. According to the calculation of the partial density of states of the surface atoms, strong mercury interactions with the surface cause a significant overlap between the d-state of mercury and the s-states of Cu. (C) 2012 Elsevier B.V. All rights reserved.