In this study, ammonia was decomposed into hydrogen and nitrogen gas by DBD plasma at different ammonia-argon gas base concentrations of 0.5% and 2% in plate type reactor. The effect of zirconia catalytic material on ammonia decomposition was investigated. Furthermore, it was found that the energy density has a positive effect on the outcome of hydrogen gas concentrations for both ammonia concentration experiments. Additionally, it was clear that hydrogen concentration increased with increasing plasma ammonia decomposition residence time. The hydrogen concentration results obtained by plasma-catalyst mode from ammonia concentration of 2% were much higher than that obtained from plasma only experiment. Also, the hydrogen concentration results at different input energy density for NH3 decomposition with and without the zirconia catalyst system were compared. It can be concluded that the hydrogen concentration of the plasma-catalyst system was much higher than plasma only. It was observed that the addition of zirconia catalytic material into ammonia decomposition process was affected by the physical and electrical properties of the gas discharge. The energy efficiency of both ammonia concentrations experiments was compared, it was seen that the maximum energy efficiencies at NH3 concentration of 2% was 0.1948 % while at 0.5% NH3 concentration was 0.084%.