Bentonite is an inexpensive, matrix for enzyme immobilization and has been frequently utilized for this purpose. In addition to its low cost, bentonite has several advantages for use as a support; including its lack of toxicity and chemical reactivity, allowing easy fixation of enzymes. In this article, Candida rugosa lipase was non-covalently immobilized on bentonite. The properties of immobilized enzyme were defined. Optimum pH and water content were determined as 7.5 and 100 mu L, respectively. The patterns of heat stability indicated that the immobilization process tends to stabilize the enzyme. Half-lives of the immobilized enzyme at 50, 60, and 70 degrees C were 45, 15, and 4 min, respectively, whereas for the soluble free lipase,it was 17 min at 50 degrees C. Kinetics were tested at 37 degrees C following the hydrolysis of olive oil and obeys the Lineweaver-Burk type of rate equation. The K-m was 4 x 10(-2) mM and the V-max was 15 mmol h(-1) mg(-1). (c) 2004 Elsevier Ltd. All r ights reserved.