Cumene peroxide is an important oxidant in the chemistry industry; however, the conversion and selectivity of cumene peroxide are still not desirable in the practical preparation process because there are some side reactions occurring in the high conversion. Hence, the reaction mechanism is investigated by many researchers. Fortunately, the high catalysis performance polymeric catalyst for cumene peroxidation was successfully synthesized in a previous study, thus, the reaction mechanism is to be investigated in this study. Except for cumene peroxide, three by-products, including acetophenone, 2-phenyl-2-propanol, 1-methylethenyl benzene of cumene peroxidation are identified from the results of high performance liquid chromatography (HPLC), gas chromatography mass spectroscopy (GC-MS), H 1 -NMR analysis. Furthermore, the mechanism of cumene peroxidation catalyzed by cobalt(II)-chelated copolymer is also proposed herein. The initiation rate equation represents r i ¼ k[cumene] 1.0 [polymer-Co(II) complex] 0.5 according to the kinetic study of cumene peroxidation catalyzed by metal-chelated copolymer. Meanwhile, the activation energy of cumene peroxidation by metal-chelated copolymer catalyst is 10.7 kcal/mol, which is located in the range of radical reactions. a High performance liquid chromatograph (HPLC, LC-9A Shimadzu Ltd. Co.) with TSK gel ODS-80TM (Shimadzu) column. b Gas chromatography online mass spectrophotometry (GC-MASS, VG-70-250S). c H 1 -Nuclear magnetic resonance (Bruker AMX-200 FT-NMR spectrophotometer).