Effects of an externally applied magnetic field on the thermal plasma treatment of non-degradable greenhouse gas were investigated. Tetrafluoromethane (CF4) was decomposed as a waste gas, because it is the most stable species among perfluorocompounds and has the highest global warming potential. A permanent magnet equipped on the exit region of a hollow electrode plasma torch produced azimuthal Lorentz force to drive rotational motions of the arc root and the thermal plasma jet. In order to sustain a stable arc discharge, the position of the permanent magnet was determined by numerical analysis on the temperature distribution according to the length of arc column. Forcibly swirling motion of thermal plasma jet was observed in accordance with the strength of applied magnetic field. Increased destruction and removal efficiency of CF4 was measured in torch operation with the externally applied magnetic field due to the enhanced entrainment of waste gas into the thermal plasma jet. (C) 2012 Elsevier B. V. All rights reserved.