The reaction mechanism of ozone and singlet carbene has been studied by means of the Gaussian-3 method to optimize the geometries of reactions, transition states, intermediates and products. The energies and structures of the important transition states, intermediates are reported for the first time. The results show that there are two different reaction pathways on the reaction of singlet carbene and ozone: the two reaction pathways may take place under suitable condition and nucleophilic reaction is relatively easier. Furthermore, two reactions are strong exothermic reactions.

Key words: CARBENE, OZONE, REACTION MECHANISM, TRANSITION STATE, GEOMETRICAL ISOMERISM