BACKGROUNDOlive oil mill wastewaters (OOMW) have caused major environmental problems because of the high organic load, high total suspended solids, high inert chemical oxygen demand (COD), low pH, a characteristic odour, its dark colour and toxicity to plants. A pulsed high-voltage discharge (PHVD) process was developed as a novel alternative to advanced oxidation processes for effective treatment of OOMW.