The performance of 1,1,1,2-tetrafluoroethane or HFC-134a decomposition and the formation of byproducts in a dielectric barrier discharge plasma reactor were studied with different packing systems such as α-Al2O3 (porous and nonporous), γ-Al2O3 (porous) and ZrO2 (nonporous). Experimental variables such as reactor temperature, initial HFC-134a concentration and oxygen levels were chosen for the performance analysis. Among the packing systems, the porous γ-Al2O3 and α-Al2O3 decomposed HFC-134a much more effectively than the nonporous α-Al2O3 and ZrO2. The combination of the plasma with the porous γ-Al2O3 was found to cover a wide range of initial concentration. The decomposition efficiency tended to increase with the addition of oxygen up to 2%, but further increase in the oxygen led to a decrease. As well as carbon oxides (CO2 and CO), significant amounts of unwanted byproducts such as COF2 and CF4 were also identified in the effluent gas with the nonporous α-Al2O3 and ZrO2. On the contrary, with the porous γ-Al2O3 and α-Al2O3, such unwanted byproducts were considerably suppressed, enhancing the formation of CO2 and CO.