AbstractAn enzyme preparation that could detoxify parathion and eight other organophosphate pesticides was covalently bound to either porous glass or porous silica beads. This immobilized‐enzyme system was examined for its use in detoxification of pesticides in production wastewaters. The kinetics of parathion hydrolysis were examined at flow rates up to 96 liter/hr and at influent substrate concentrations ranging from 10–250 mg/liter. The enzyme reactor was able to hydrolyze 95% o1r more of the parathion added to industrial wastewaters generated during its production, thus reducing the effluent parathion concentration to below 500 ppb. Laboratory continuous‐flow experiments were conducted for 70 days with industrial wastewater and indicated no loss in immobilized‐enzyme activity. The influence of pH, temperature, solvents, and detergents on enzyme stability and activity and enzyme reactor kinetics will be discussed.