The effect of bubble-side, mass transport limitations on performance of the catalytic fluidized-bed reactor is investigated. The reactor model of Werther (1980) is extended by introducing such resistance in its original formulation in the form of a dimensionless Blot number. Correlations for the Biot number are proposed. The modified model is contrasted with the original model to assess the extent of such resistance. It is shown that fluid-bed reactor performance is affected especially in the case of Geldart type-B particles and at low NTUs.