Perfluorocompounds emitted by the semiconductor industry are global warming gases. These gases need to be removed efficiently because of their strong absorption of infrared radiation and long atmospheric lifetimes which cause the global warming effect. In this study, microwave argon plasma operating at atmospheric pressure was investigated experimentally for various operating conditions including microwave power, total gas flow rate, initial concentration, and additive gas. The mechanisms of perfluorocompounds decomposition were studied by the plasma emission spectrum. Under the optimum condition, the destruction and removal efficiency of CF4 Could reach up to 98.4%. The emission spectrum analysis indicated that the existence of the O or OH radicals could enhance the CF4 decomposition by adding suitable volume of O-2 or H2O. The mechanisms of CF4 decomposition are that the electron, O and OH radicals all associated with CF4 conversion, it has the sequence that enough effective electrons reacted with CF4 to form CFi radicals, O and OH radicals further reacted with CFi radicals to convert CF4 into CO2 and HF (C) 2009 Published by Elsevier B.V.