Density-functional theory and a pseudopotential plane-wave approach are employed to study the structural and electronic properties of oxygen on CdTe (001) and (111) surfaces. The energetically favored configuration for oxygen adsorption on CdTe (001) is that where the O adatoms are located at the Cd-terminated B site, while 0 adatoms are at the Cd-terminated H-3 site of CdTe (111) surface among the structures examined. Some possible surface defects are also examined on CdTe (001) and (111) surfaces. Oxygen can easily diffuse into the CdTe substrate at the (111) surface compared with the (001) surface. (c) 2012 Elsevier B.V. All rights reserved.