Electrochemical sterilization of the marine gram-negative bacterium Vibrio alginolyticus cells was carried out using basal-plane pyrolytic graphite electrode modified with adsorbed ferrocene. When cyclic voltammetry was taken in V. alginolyticus cell suspension using an electrode modified with ferrocene at a scan rate of 20 mV per s at 25 degrees C, an electrocatalytic oxidation occurred above 0.1 V versus saturated calomel electrode (see). Peak current was observed around 0.3 V vs see. The bacteria which attached to the ferrocene modified electrode were sterilized at 0.2 V vs see in sterile seawater, whereas they were sterilized at 0.8 V vs see when using a bare graphite electrode. This sterilization was due to the electrochemical oxidation of the intracellular substance and not to the toxicity of ferrocene. V. alginolyticus cells in sterile seawater were completely sterilized after 10 min by applying 0.2 V vs see.