Nano-polyhedral(Co,Mn)_3O_4was synthesized by sol-gel method,and its catalytic properties and reaction mechanism for degradation of 1,2,4-trichlorobenzene were studied in detail.The product was characterized by gas chromatography and gas chromato-graphy-mass spectrometry(GC-MS).The results showed when 200 mg nano-polyhedral Co_3O_4 reacted with 1.5μL 1,2,4-trichlorobenzene at 300℃ for 60 min,the degradation efficiency was 92%.In addition,hydrodechlorination occured dominantly during the process.