The　rational　design　of　low-cost　transition　metal　catalysts　that　exhibit　high　activity　and　selectivity　may　be　the　most　significantly　investigated　in　heterogeneous　catalysis.　In　this　study,　Co3-xMnxO4　(x　=　0.75,　1.0,　and　1.5)　mixed　metal　oxides　were　successfully　synthesized　by　a　controlled　template-free　autoclave　strategy　and　studied　for　toluene　oxidation.　It　is　found　that　the　Co-rich　sample　showed　markedly　enhanced　activity　and　the　3D　dandelion-like　Co2.25Mn0.75O4　catalyst　exhibited　in　the　highest　toluene　oxidation　rate　(8.9　mu　mol/(g(cat)s))　and　a　100%　toluene　conversion　at　239　degrees　C.　In　situ　DRIFTS　study　indicates　that　toluene　was　sequentially　oxidized　to　benzyl　radical,　benzaldehyde,　benzene,　oxalic　acid,　and　finally　to　CO2　and　H2O.　The　interaction　between　Co　and　Mn,　in　conjunction　with　the　high　concentration　of　surface　oxygen　species　and　rich　surface　oxygen　vacancies,　reasonably　explains　the　elevated　catalytic　activity　and　thermal　stability　for　toluene　oxidation　over　3D　flower-like　Co3-xMnxO4　spinel　catalysts.