Partially purified intracellular inulinase from Kluyveromyces sp. Y-85 was immobilized covalently by adsorb-crosslinking onto a macroporus ionic polystyrene beads. Using a 4.5% (w/v) fructan solution from Jerusalem artichoke tuber as substrate, in a continuous bed column reactor packed with 70 mi of the immobilized inulinase beads, the maximum volumetric productivity of 234.9 g reducing sugars l(-1) h(-1) was obtained with fructan hydrolysis of 75%. The hydrolytic product was a mixture of 85% D-fructose and 15% D-glucose. The half-life of the bioreactor was estimated to be 32 days.