Ozone, generated by a pulsed power corona discharge, was usedto degrade pentachlorophenol (PCP). The degradation of PCP wasdriven by ozone and superoxide radical (SOR). The coronadischarge reactor was made without glass dielectric material,not only to reduce the power consumption but also to enhancethe formation of the SOR. In addition, the corona dischargedevice was operated with pin-plate or pin-ring typeelectrodes, which had a normal and parallel oxygen flow,respectively. The ozone generated in the corona dischargereactor was in the range of 0-0.39 mg min-1. To confirm the generation of SOR, the hydrogen peroxide was measuredunder acidic conditions without ozone effects. PCP at 10 ppm wascompletely degraded in 10 min in both electrode types withnegative high DC voltage. The degradation rate of PCP was muchgreater at a high frequency (1 kHz). Oxalic, malonic andglyoxylic acids were generated as final products of the reaction.