The preparation, characterization of CaO and its application in the catalytic ozonation of cinnamaldehyde to benzaldehyde were studied. The calcination temperature greatly affected the physicochemical properties of CaO, and the CaO calcined at 900 degrees C exhibited the optimal ozone utilization efficiency. When using 0.20 g CaO calcined at 900 degrees C, 750 mLmin(-1) oxygen flow rate for generating O-3, and reacted at 0 degrees C for 210 min, the cinnamaldehyde conversion reached 97.77%, as well as the benzaldehyde yield was 59.51%. And the cinnamaldehyde conversion in a catalytic ozonation on CaO catalyst maintained above 90% for four used cycles, which exhibited reasonable catalyst stability. The electron donating process of surface O2- on the catalyst is the key to improve the benzaldehyde yield, and based on the intrinsic kinetic study, the Eley-Rideal kinetic model with cinnamaldehyde being adsorbed was the appropriate model for the catalytic ozonation of cinnamaldehyde on CaO. (c) 2017 American Institute of Chemical Engineers AIChE J, 63: 4403-4417, 2017