Influence of oxidizing and reducing pretreatment on the catalytic performance of CeO2 for CO oxidation

•A study on the effects of oxidation (O2) and reduction (H2) pretreatment over CeO2 and catalytic response of CO oxidation.•Higher pretreatment temperatures led to increase crystallite sizes, decrease specific surface areas and decrease number of defect sites.•Higher specific surface area and defect sites improve the CO conversion.