Alcohol oxidase (AOX), in the presence of oxygen, catalyzes the bioconversion of short-chained alcohols into their corresponding aldehydes and ketones. Alcohol oxidase can be used in the production of aldehydes that can serve as precursors of flavor compounds and fine chemicals. However due to AOX's poor stability, its practical industrial or analytical application is limited. Two kinetic inactivation regions suggest that one of AOX's isozymes is more resistant to thermal inactivation at atmospheric or high pressures. The resistant fraction was 4-34 times more stable than the labile fraction. High hydrostatic pressure (HHP) stabilized AOX against thermal inactivation. A 14-fold stabilization was observed at 49.4 degrees C for the labile fraction at 200 MPa relative to atmospheric pressure. The activation energy of inactivation at 40-160 MPa ranged from 95 to 184 kJ mol(-1) for the resistant fraction and from 232 to 402 kJ mol(-1) for the labile fraction. The activation volume of inactivation was independent of temperature and of approximately 20 cm(3) mol(-1).