Hexafluoropropylene(C₃F₆, HFP) was synthesized from the pyrolysis of trifluoromethane(CHF₃, R23). Product distributions were estimated by the computer simulation for the pyrolysis of R23 using the kinetic constants for individual reaction mechanisms proposed by other researchers. Based on the computer simulation, the pyrolysis of R23 was investigated in the reaction conditions such as reaction temperature 700-1000℃, contact time 0.01-14 sec and molar ratio R23/tetrafluoroethylene (CF₂=CF₂, TFE) 0.2-2.5. We found that the recycling of unreacted R23 and TFE in the product is to be useful to obtain a high yield of HFP and to stabilize the reaction temperature.