This study of the water-contamination reactions of ethylene oxide was conducted by Artbur D. Little, Inc. with finding from, and under the auspices of the Ethylene Oxide Industry, Council, part of the American Chemistry Council. Significant experimental and technical contributions were also made oy staff from Shell Chemicals Westhollow, Technology, Center in Houston, Texas, and Union Carbide Corporations Research Center in South Charleston, Test Virginia. Unique fourth-order kinetics for the reactions of ethylene oxide with water, and ethylene oxide with ethylene glycols were derived and validated, as were kinetics for tbe reactions of neat ethylene oxide and the decomposition of ethylene glycols, The latter data was incorporated into a reaction model useful the determination of ethylene oxide storage stability and pressure relief system design under water-contamination scenarios.