The adsorption of O-2 on the clean and Mg doped LaFeO3 (0 1 0) surface has been investigated using the density functional theory (DFT) method. Calculation results show that Mg-doping can change the electronic properties of LaFeO3 (0 1 0) surface by decreasing the band gap. When Mg ions were not on the first layer of the surface, with increasing Mg content the adsorption of O-2 was enhanced. When Mg ions were on the first layer, the adsorption of O-2 was weakened with the increase of Mg content. The analysis results of the DOS indicated that the Mg ion and adsorbed O-2 had no strong hybridization, and the bonding mechanism was originated from the strong hybridization between the O p and Fe d orbital. Referring to all the calculation results, it was found that except for the increase of stability of oxygen adsorption, the Mg doping could not improve the sensitivity to O-2. (C) 2012 Elsevier B.V. All rights reserved.