Chemical reactions of toluene, xylene, MEK, and TCE in plasma were studied to investigate the potential application of a low-temperature plasma process for the removal of concentrated VOCs. These compounds were decomposed in plasma and solidified by plasma polymerization. Toluene and xylene showed higher solidification efficiencies than did MEK and TCE. Their solidification efficiencies reached almost 100% when the supplied energy per unit mass of gas was more than 5 × 108 J/kg. The low solidification efficiencies of MEK and TCE were attributed to the abstraction of oxygen atoms in MEK and chlorine atoms in TCE. The high solidification efficiencies were maintained when the air and moisture contents were less than 40 %. FT-IR spectra showed that the chemical structures of the solidified VOCs were different from those of the pure VOCs, indicating that the VOC molecules were decomposed prior to solidification. When the VOCs were mixed, the solidification efficiencies ranged between those of the individual species.