Abstract: Method and apparatus for blood and tissue detoxification by oxidation of excess undesirable or toxic substances such as ammonia, urea, creatinine, alanine, carbon monoxide, drug overdoses, uric acid, actone, aceto acetate and ethanol in an electrochemical cell which may be implanted or used in an extracorporeal shunt system. The cell may be hybridized with a battery to drive the cell under certain conditions, and the cell may be employed as part of a blood toxic substance level monitoring system. The invention is typified by the case where electrochemical cells convert oxygen and the enumerated toxic substances in the body fluids to harmless products such as CO.sub.2, water and nitrogen which are easily dissipated. The cells have hydrophobic cathodes having a membrane thereover of silicone rubber, polyfluorocarbon, polycarbonate, and copolymers thereof which permit diffusion of oxygen therethrough.