Three-dimensionally ordered macroporous (3DOM) Co CoxCe1-xO delta oxides with different Co/Ce atomic ratios were synthesized by a colloidal crystal template (CCT) method. They show higher activity for soot combustion in O-2 than single CeO2 and Co3O4 under loose contact conditions. XRD, Raman, XPS, H-2-TPR and soot-TPR characterizations were carried out to study the surface and bulk oxygen vacancies and to correlate them to the activity. There exists electron transfer from Ce to Co in the matrix. Both Ce3+ and Co2+ species contribute importantly to the creation of surface and bulk oxygen vacancies, which determine the ignition and burnout temperatures of the catalysts, respectively. (C) 2018 Elsevier Inc. All rights reserved.