The influence of polarization on the probe reaction CO oxidation is studied thanks to DFT calculations. Following recent experimental results and common behaviors on metal oxides, a Mars–Van Krevelen mechanism is adopted. The adsorption of CO is thus firstly studied, illustrating both the role of polarization and the one of termination. While P_$up$ TiO₂ termination presents the most favorable interaction with CO, allowing a spontaneous oxidation in CO, an activation barrier has to be overcome on P_$down$ domain. Given the ability of BaTiO₃ for CO oxidation, desorption of CO appears as the rate determining step on both terminations, but again polarization can be used to go over this issue. Finally, recovery of BaTiO₃ slab through O dissociation also behaves diversely depending on the termination and on the polarization. Through this study we thus demonstrated the key role of polarization to improve CO oxidation