The toxicology of the widely used oxygenated fuel additive methyl tert-butyl ether (MTBE) has recently attracted considerable interest in the public sector. In this study, a radio-frequency (RF) plasma reactor was used to decompose MTBE gas. The effects of two important plasma operational parameters - including power consumption per unit volume of the plasma (W-D, Wcm(-3)) and MTBE feeding concentration (C-MTBE,%) - for MTBE decomposition were investigated in detail. The results show that the MTBE decomposition efficiency (eta(MTBE)) increases with increasing W-D and with decreasing C-MTBE. In this study, the results reveal that, in the MTBE/Ar plasma, the eta(MTBE) was over 99.9%, which occurred at the conditions of for W-D = 0.96Wcm(-3), C-MTBE = 3%, 20 Torr of operational pressure and a 100 cm(3 .) min(-1) total gas flow rate. In particular, the effects of W-D and C-MTBE for the species detected in the effluent gas stream are carefully discussed. In addition, the deposition problem which occurred in the reactor was examined by means of Scanning Electron Microscopy (SEM).