The adsorption of isomaltose from high sugar concentrated reaction mixture was systematically investigated using static experiments. The isotherm data for the single-components glucose, fructose, and isomaltose fit the Langmuir adsorption model well. The product isomaltose has much more affinity for the zeolite than the other carbohydrates, which allows in situ separation process. Isomaltose is separated in situ from the enzyme reaction mixture by dealuminated beta-zeolites (Si/Al = 75) to avoid further reactions involving it. (C) 2003 Published by Elsevier B.V.