Dielectric barrier plasma reactor using AC power was applied to the decomposition of toluene. Natural zeolite of 4.75-6.7 mm and glass beads of 4 to 6 mm in diameter were used as the dielectric packing materials. The effects of the dielectric packing materials, the oxygen content, the peak voltage, the voltage polarity on the decomposition of toluene and the power delivery were examined. When the dielectric materials such as glass beads and natural zeolite were packed in the reactor, the performance for the decomposition of toluene and the discharge power increased. Despite the adsorption capability, the zeolite showed similar decomposition performance to the glass beads, which indicates that the adsorption capability does not affect the decomposition of toluene in steady state condition. In the absence of the dielectric packing material, higher voltage was required to decompose toluene. As the oxygen content was increased, the decomposition efficiency slightly increased. When the AC voltage was rectified to positive or negative half-wave, the discharge power and the decomposition efficiency greatly decreased. The decomposition efficiency of toluene was identical, regardless of the voltage polarity changed by half-wave rectification. Although the thermal incineration has larger decomposition rate constant than the dielectric barrier plasma process , it requires a lot of thermal energy to heat the gas to a high temperature, and thus the dielectric barrier plasma process is considered to be sufficiently competitive to the thermal incineration.