Treatment of H2S and NH3 using the non-thermal plasma (NTP) methods was investigated. Two NTP systems were used in this study, one consisting of a multicell plate-to-wire reactor (PTW), and the other consisting of an ozonization chamber and the multi-cell PTW reactor. Each cell of the PTW reactor had a sheet of copper foil embedded in dielectric lavers as its high voltage electrode and a wired rack as its gounded electrode, Use of the wired rack type electrode allowed large flow throughput, and promoted intense local electric fields. The experiments showed that under constant energy input. the decomposition efficiency. of H2S or NH3 decreased with increasing initial concentration of the gas, and increased with increasing injected ozone and relative humidity. Injection of NH3 into H2S stream did not improve the H2S decomposition efficiency but was necessary for removal of sulfite-containing compounds in the discharge air.