A　series　of　cobalt-based　spinel　composite　metal　oxides　doped　with　alkaline　earth　metals,　viz.,　MxCo3-xO4　(M　=　Mg,　Ca,　Sr　and　Ba;　x　=　0,　0.1,　0.3,　0.5,　0.7　and　0.9),　were　prepared　by　the　coprecipitation　method　and　characterized　by　XRD,　SEM,　nitrogen　sorption,　H2-TPR,　O2-TPD-MS　and　XPS;　the　effect　of　alkaline　earth　metal　doping　on　the　catalytic　performance　of　MxCo3-xO4　composites　in　N2O　decomposition　was　investigated　in　a　fixed　bed　micro-reactor.　The　results　showed　that　after　doping　with　the　alkaline　earth　metals,　the　particle　size　of　MxCo3-xO4　catalysts　is　decreased,　accompanying　with　an　increase　in　the　specific　surface　area　and　the　amount　of　surface　adsorbed　oxygen　and　Co2+　species.　Meanwhile,　the　redox　performance　and　catalytic　activity　of　MxCo3-xO4　in　N2O　decomposition　are　also　greatly　enhanced.　Under　the　conditions　of　0.68%　N2O,　3%　O2　and　Ar　as　balance　gas,　the　Sr0.7Co2.3O4　catalyst　doped　with　Sr　(x　=　0.7)　exhibits　highest　activity　in　N2O　decomposition;　the　reaction　temperatures　where　the　N2O　conversion　reaches　10%　and　95%　are　as　low　as　312　and　451℃,　respectively.　©　2018,　Science　Press.　All　right　reserved.