Toluene decomposition was carried out using nonthermal plasma reactors, which were packed with spherical ferroelectric pellets [SrTiO(3) (epsilon = 330) or BaTiO(3) (epsilon = 15,000)]. The former showed higher efficiencies for toluene decomposition and suppression of NOx formation than the latter. To clarify the difference in effectiveness between SrTiO(3) and BaTiO(3), the waveforms of applied voltage and discharge current were investigated in detail using an oscilloscope. Many discharge current pulses were observed in both reactors when plasma discharge was generated. However, plasma conditions, such as maximum value and numbers of pulsed discharge current peaks in one cycle, differed greatly between the two reactors even at the same input power. The results suggested that plasma conditions could be changed by changing the ferroelectric pellets in the packed-bed plasma reactor. We proposed different models of discharge mode in the two plasma reactors, based on the effect of the ferroelectrics on plasma reaction.