It is well known that PFC (PerFluoroCompound) gases are considered as serious global warming material. Therefore, international efforts like the Kyoto Protocol have been made for reducing such global warming gases. In order to decompose a large quantity of PFC gases exhausted from semiconductor production processes, an air plasma torch with hollow electrodes has been employed for a thermal plasma pyrolysis system in this research. A mixture of 1% CF4 and the rest N2 purging gas was used as waste gas. First, the decomposition temperature of CF4 and the plasma thermal power to achieve a sufficient destruction and removal efficiency (DRE) of CF4, are estimated from the chemical equilibrium calculations based on the minimization of Gibbs free energy. Second, effects of waste gas flow rate on the decomposition process were examined by numerical analysis. The maximum flow rate of waste gas was 1,000 L/min and the maximum input power of the plasam torch was 90 kW. Finally, decomposition experiments for the waste gas including CF4 were carried out after setting up the plasma pyrolysis system, and the DRE of CF4 was measured by the quadrupole mass spectrometry.