The degradation of chlorobenzene in aqueous solution by pulsed power plasma was studied. 100% degradation of 200 mg/L chlorobenzene happened in both liquid and gas phase after 12 min and dechlorination efficiency of 85.3% was obtained after 20 min. The energy efficiency corresponding to 50% chlorobenzene degradation was 3.14 g/kWh. The plasma degradation efficiency of chlorobenzene was inversely proportional to the initial concentration, conductivity and alkalinity of the solution. The study of effect of pH and scavengers on chlorobenzene removal revealed the major role of OH radicals in the degradation. The major intermediate compounds were benzene derivatives including various chlorinated and nitrogenous organics and their concentration decreased significantly after 20 min of plasma treatment. Organic acids such as acetate, formate and oxalate were also produced, which contributed to a part of remaining TOC (total organic carbon) in the solution. The degradation pathway of chlorobenzene involving various oxidative and reductive species is proposed. The disc diffusion test confirmed the complete detoxification of chlorobenzene solution after treatment. © 2019 Elsevier Ltd.