Nanocubic CeO2 based oxides with varied contents of surface VO were synthesized. CeO2 exhibits higher soot oxidation activity and stability than CeO2-ZrO2. Excessive surface oxygen vacancies induce the formation of O2− rather than Ox−. Incomplete regeneration of O2− causes deactivation during soot oxidation. High Ox− availability brings about superior stability of CeO2 during the reaction.