The direct conversion of methane and carbon dioxide to produce C-4 hydrocarbons (C4H8, n-C4H10 i-C4H10) and synthesis gas (H-2 + CO) was investigated over quartz fleece, zeolite NaA, zeolite NaY, and zeolite HY catalysts promoted by dielectric-barrier discharges (DBDs) at relatively low temperatures and ambient pressure. Both pore size and electrostatic properties of zeolites influence the reaction under plasma conditions. Zeolite HY is the most promising catalyst in producing synthesis gas (H-2 + CO) and C-4 hydrocarbons (C4H8, n-C4H10, i-C4H10) with high selectivity at low temperatures and ambient pressure. The important variables affecting the activity and selectivity of a zeolite HY catalyst in a DBD reactor such as temporal stability, discharge power, mixing ratios of methane to carbon dioxide, space velocity, operating pressure, and wall temperature were studied. The conversion of methane was 55.1% and that of carbon dioxide 26.7%, and the selectivity to CO was 21.7% and that to C4 hydrocarbons reached 52.1% when the reaction was performed at a wall temperature of 423 K, gas pressure of 1 bar, molar ratio of methane/carbon dioxide of 3:1, feed gas flow rate of 200 mL/min, and discharge power of 500 W.