The traditional process for the reduction of SO2 by CH4 usually leads to enrichment of the effluents with H2S and CO2. In this study, a radio-frequency (RF) plasma system was applied to generate useful byproduct: syngas (H-2 and CO) at room temperature. Experimental results indicate that the H-2/CO ratio increased with the elevation of inlet [CH4]/[SO2] ratio (R), or the decrease of applied power (E) or operational pressure (P). H-2/CO values ranged from 1.34 to 4.28 and reached 2.09 and 1.9S for E = 90W and 120 W, respectively, at R = 1 and P = 4000 N m(-2). At first the selectivity to CO increased with the elevation of R or E, while the selectivity to H-2 was only decreased at R > 2 whatever the power that was supplied. However, at R = 2, optimum selectivities of H-2 and CO, and decomposition efficiencies of CH4 and SO2, were achieved. The decomposition efficiencies and product components strongly depend on E or R. CH4 is more easily decomposed than SO2 and yields mainly syngas, with traces of CO2, C2H2, and C2H4. In addition, sulfur-containing compounds including major amounts of CS2, elemental sulfur and minor amounts of COS, but no toxic H2S, were observed. The formation pathways of syngas are also proposed to provide useful information to gain insight into the CH4 conversion in the FT plasma. (C) 2003 Society of Chemical Industry.