The reaction mechanisms for the oxidation of isopropanol and propylene to acetone over the 10% V2O5/TiO2 catalyst were modeled according to the results of FTIR, microcalorimetric adsorption and microreactor kinetics. The two reaction mechanisms are closely correlated since isopropanol can be taken as the intermediate for the oxidation of propylene to acetone. The simulations revealed how the reaction conditions affect surface coverages that in turn influence the reaction activities. The abstraction of a-H from the surface isopropoxy groups by the oxidation sites (V5+-O) is the rate-limiting step for the oxidative dehydrogenation of isopropanol to acetone, while the adsorption of propylene on surface Bronsted acid sites (V-OH) to form the Surface isopropoxy groups is the rate-limiting step for the selective oxidation of propylene to acetone. Both Bronsted acid sites and oxidation sites (V5+-O) are required for the conversion of propylene to acetone. Thus, one way to promote the rate of propylene adsorption in order to enhance the rate of propylene conversion to acetone may be to increase the strength of the Bronsted acid sites by adding some other acidic materials. The oxygen deficient vanadium sites were found to promote the dissociative adsorption of isopropanol to form the surface isopropoxy groups and the adsorption of water to form the surface Bronsted acid sites (V-OH) needed for the adsorption of propylene. (C) 2003 Elsevier Science B.V. All rights reserved.