This study employed radio-frequency (RF) plasma for decomposing benzene (C 6 H 6 ) gas, and examined both gaseous products and solid depositions after reaction. The reactants and products were analyzed mainly by using both an on-line Fourier transform infrared (FT-IR) spectrometer and a gas chromatography. The analyses for solid deposition included electron spectroscopy for chemical analysis (ESCA), element analysis and heat value analysis. The C 2 H 2 , C 2 H 4 , C 2 H 6 , CH 4 , CO 2 and CO were detected and discussed. The analytical results demonstrate that in the C 6 H 6 /Ar plasma, C 2 H 2 is the sole gaseous product being detected. The fraction of total carbon input converted into C 2 H 2 (YC2H2) increased with increasing C 6 H 6 feed concentration, but decreased with increasing input power. In the C 6 H 6 /H 2 /Ar system, besides C 2 H 2 , CH 4 , C 2 H 4 and C 2 H 6 were also detected, and their yields increased with increasing H 2 /C 6 H 6 ratio. The above results indicated that the addition of H 2 (auxiliary gas) achieves the benefit of creating hydrogen-rich species like CH 4 , C 2 H 4 and C 2 H 6 . In the C 6 H 6 /O 2 /Ar system, C 6 H 6 could be totally oxidized into CO 2 , CO and H 2 O, and no measurable phenol was found. Analyses of solid depositions revealed that the carbon depositions were similar to those of Anthracite. The carbon deposition has a heat value of 7000kcal/kg. Additionally, the possible reaction pathways were also built up and discussed.