Aryl alcohol oxidase was immobilized on two mesoporous materials, MS-A and MS-B. The immobilization rate for the larger pore material MS-A (11.5 nm) was higher than for the smaller pore material MS-B (4.2 nm). Furthermore, the sol-gel silica encapsulation of MS-immobilized enzymes improved thermal stability. (C) 2009, The Society for Biotechnology, Japan. All rights reserved.