Catalase was covalently immobilized onto florisil via glutaraldehyde (GA) and glutaraldehyde +6-amino hexanoic acid (6-AHA) (as a spacer arm). Immobilizations of catalase onto modified supports were optimized to improve the efficiency of the overall immobilization procedures. The V-max values of catalase immobilized via glutaraldehyde (CIG) and catalase immobilized via glutaraldehyde +6-amino hexanoic acid (CIG-6-AHA) were about 0.6 and 3.4% of free catalase, respectively. The usage of 6-AHA as a spacer arm caused about 40 folds increase in catalytic efficiency of CIG-6-AHA (8.3 x 10(5) M-1 s(-1)) as compared to that of CIG (2.1 x 10(4) M-1 s(-1)). CIG and CIG-6-AHA retained 67 and 35% of their initial activities at 5 degrees C and 71 and 18% of their initial activities, respectively at room temperature at the end of 6 days. Operational stabilities of CIG and CIG-6-AHA were investigated in batch and plug-flow type reactors. The highest total amount of decomposed hydrogen peroxide (TAD-H2O2) was determined as 219.5 mu mol for CIG-6-AHA in plug-flow type reactor. (C) 2011 Elsevier Inc. All rights reserved.