The mass transfer coefficients and Sherwood numbers for catalyzed fluid cracking catalyst particles were measured and computed in a two-dimensional (2-D) bubbling fluidized bed, with ozone decomposition reaction. The measured and computed Sherwood numbers, using 3- and 2-D kinetic theory based computational fluid dynamics simulations, were of the order of 10-610-2. The low Sherwood numbers were in reasonable agreement with the literature data for small particles, at low Reynolds numbers. The computational fluid dynamics simulations showed that it is possible to compute conversions in fluidized bed reactors without using the conventional model with empirical mass transfer coefficients. (c) 2011 American Institute of Chemical Engineers AIChE J, 2012