Al-doped　Co3O4　and　CoO　are　prepared　from　CoAl　hydrotalcite　by　calcination　in　air　and　N2　atmospheres,　and　characterized　by　TG-DTA,　XRD,　SEM,　N2　adsorption,　Raman,　XPS,　and　H2-TPR.　CoAl　hydrotalcite　is　oxidized　to　Co(Co,Al)2O4　in　air　accompanying　with　the　collapse　of　layered　structure,　while　in　N2　it　decomposes　to　Co(Al)O　that　remains　the　plate　morphology　of　hydrotalcite.　In　both　cases,　Al3+　is　doped　into　the　lattice　of　cobalt　oxides,　leading　to　marked　changes　in　the　crystal　size,　surface　state,　and　reducibility.　Especially,　Al-doped　CoO　shows　smaller　crystal　size　(4.1　nm),　larger　surface　area　(172　m2　g1),　and　higher　degree　of　structural　disorder　than　Al-doped　Co3O4.　Meanwhile,　the　Al-doped　cobalt　oxides　show　different　reducibilities　to　those　of　Co3O4　and　CoO,　indicating　a　strong　interaction　between　cobalt　and　aluminum.　The　N2-calcined　sample　exhibits　higher　activity　for　benzene　combustion　than　the　air-calcined　sample　as　well　as　a　relatively　good　stability　during　heating/cooling　cycles　and　a　good　long-time　durability.　Under　the　reaction　atmosphere,　Co(Al)O　is　transferred　to　Co(Co,Al)2O4.　The　resulting　Co(Co,Al)2O4　remains　the　original　plate　morphology　and　textural　property　and　presents　abundant　surface　adsorbed　oxygen　species,　which　accounts　for　its　high　activity.　©　2022