In this study, dimethyl sulfoxide (DMSO) contaminated wastewater was attempted to be treated by the streamer corona discharge process, which was composed of the pulsed high voltage power and needle to plate electrodes reactor. From the comparison between the oxidized intermediates of DMSO in UV/H₂O₂ and corona discharge process, it was found that OH was a main responsible oxidant for the DMSO degradation. However, in corona discharge process, DMSO was directly mineralized to sulfate ion during the degradation time in contrast to UV/H₂O₂ process. This behavior was likely due to the highly concentrated production of OH in and around the plasma channel formed by high voltage corona discharge in water. The experimental result, which shows the increased removal efficiency of DMSO with increasing initial DMSO concentration, can be also explained by the locally concentrated OHs in the plasma channel.