The adsorption of CO2 on K1-yNayTa1-xNbxO3 (KNTN) surface terminations has been studied using density functional theory. The preferred adsorption sites are found to be the Na-O bridge site on the K(Na)O-termination and O top site on the Ta(Nb)O-2-termination. In the most favorable configurations, the CO2 molecule is bent and the C-O bonds are elongated, indicating the CO2 activation. After adsorption, the band gap of the surface is enlarged, relevant to the electrons density redistribution. The results illustrate that the electronic structure of KNTN surface is sensitive with CO2 adsorption. The results provide fundamental insight into the CO2 adsorption mechanism on KNTN surface and potential application on gas sensing. C) (C) 2014 Elsevier B.V. All rights reserved.