This work investigated ethylene epoxidation performance using a parallel plate dielectric barrier discharge (DBD) system with a separate ethylene/oxygen feed in order to produce oxygen active species prior to reaction with ethylene. The highest ethylene oxide (EO) selectivity of 73% was obtained when the combined catalytic-DBD system was operated at an ethylene feed position of 0.5, an O-2/C2H4 feed molar ratio of 0.2:1, and an Ag loading of 10 wt %. The presence of a glass plate-supported Ag catalyst provided considerably higher EO selectivity, twice as much as that of the DBD system alone. As compared to the DBD system with an Ag catalyst supported on glass beads, the glass plate dielectric barrier was found to be a more efficient support for ethylene epoxidation. This is because the glass plate system provided plasma that was more uniform than that provided by the glass bead system.