A cysteine protease Cathepsin B purified from goat brain was microencapsulated within the CM-cellulose-Ca-alginate membrane having a, CM-cellulose, 1% CaCl2, and liquid core in it. The activity yield was maximum under the optimum conditions of immobilization mainly at 4% CM 3% alginate concentrations. The encapsulated form of enzyme could retain similar to 60% of its original activity during its reusability for more than five successive batch reactions. The physico-chemical characteristics for free and immobilized Cathepsin B were also compared. The optimum pH and temperature of free and immobilized enzyme were 6.0 and 50 degrees C, and 6.0-6.5 and 55 degrees C, respectively. The K'(m) value (1.52 mM) for the immobilized enzyme was one and half-fold higher than for the soluble enzyme. The pH and thermal stability as well as organic solvent stability were improved significantly after microencapsulation may make it useful for catalyzing some organic reactions like trans-esterification and trans-amidation. (c) 2006 Elsevier Inc. All rights reserved.