N2O decomposition has been performed on series of Co3O4 spinels with various morphologies including nanocube (NC-Co3O4), nanosheet (NS-Co3O4), nanorod (NR-Co3O4) and nanopolyhedron (NPL-Co3O4). The NC-Co3O4 having a predominant exposure of the (0 0 1) plane is more active than NS-Co3O4 and NR-Co3O4 mainly exhibiting the (1 1 0) plane. The characterization techniques such as N2 sorption, XRD, SEM, TEM, H2-TPR, OIE, and XPS as well as DFT calculation are employed to investigate their physicochemical properties. The study on morphology and crystal fringe demonstrates that oxygen vacancies are more readily generated on (0 0 1) facet which requires less activation energy (30 kJ mol-1) than that for (1 1 0) facet. Abundant surface chemisorbed reactive oxygen species, involved in N2O dissociation, were existed in the vicinity of oxygen vacancies of NCCo3O4, which could promote both N2O adsorption upon such vacancies as well as the further activation of another N2O molecule by reactive oxygen. Besides, low specific surface area and large particle size are essentially limiting the catalytic performance on N2O decomposition over NR-Co3O4 and NPL-Co3O4.