The present work reports the decomposition of a model volatile organic compound (VOC), toluene, in a packed-bed dielectric barrier discharge (DBD) plasma reactor. For this purpose, 2.5 wt% MOₓ/ɣ -Al₂O₃ (M = Mn and Co) catalysts prepared by the wet impregnation method were utilized for packing. The influence of varying input toluene concentration (between 50 and 200 ppm) and different packing conditions (surface modifications of ɣ -Al₂O₃ with Mn and Co oxides) on the conversion of toluene, product selectivity of CO and CO₂, and ozone formation were studied. Surface-modified ɣ -Al₂O₃ showed improved CO₂ selectivity compared to ɣ -Al₂O₃ and bare plasma. CoOₓ/ɣ -Al₂O₃ effectively decomposed 50-ppm toluene (95% at 3.8 W) with about 70% CO₂ selectivity. MnOₓ/ɣ -Al₂O₃ and CoOₓ/ɣ -Al₂O₃ displayed the similar conversion effect at higher toluene input. Almost 98% carbon balance and suppressed ozone formation were observed using surface-modified ɣ -Al₂O₃, signifying the necessity of integrating metal oxide to achieve effective conversion and maximum selectivity towards the desired products. The mean electron energies and electron energy distribution function were also calculated using BOLSIG+ software. The high-performance packed-bed DBD system packed with supported 2.5% MOₓ/ɣ -Al₂O₃ offers a promising approach using highly active transition metal oxide-based catalysts for VOCs removal. IEEE