An electrochemical oxidation reactor includes rotatable electrodes inside a reactor vessel. The electrodes are mounted to support plates, which in turn are mounted on shafts. The plates are attached to each other in a spaced relationship so that a gap is formed therebetween. The plates are each electrically insulated from each other. The electrodes are mounted to the inside surfaces of these plates, inside the gap. The gap is sized to receive liquid to be treated so that liquid located within the gap will react with the electrodes. An electrical charge is applied to each shaft so that a dielectric is formed across the gap within the fluid located in the gap. According to a first embodiment, an electrochemical reactor includes containing two spaced electrode support plates. According to another embodiment, an electrochemical reactor includes several spaced electrode support plates.