The decomposition of benzene was carried out using two types of plasma reactors packed with BaTiO/sub 3/ pellets: one had two electrodes made of stainless steel (SUS-reactor) and the other had glass layer between two concentric electrodes (GL-reactor). It was found that the decomposition efficiency and the suppression of N/sub 2/O and NO/sub x/ formations in the GL-reactor were greater than those in the SUS-reactor. On the contrary, the suppression of O/sub 3/ formation and the oxidation to CO/sub x/ in the SUS-reactor were superior to those in the GL-reactor. Furthermore, the effect of operating conditions, i.e., waveform and frequency of applied AC power, was also investigated using both the reactors.