A compartment model was developed to describe the flow pattern of gas within the dense zone of a tapered membrane-assisted fluidized-bed reactor (TMAFBR), in the bubbling mode of operation for steam reforming of methane under wall heat flux. The parameters of the developed model (i.e., number of compartments for the bubble and emulsion phases) were determined using the experimental data reported elsewhere [Adris AM, Lim CJ, Grace JR. The fluidized bed membrane reactor system: a pilot scale experimental study. Chem Eng Sci 1994; 49:5833-431 and good agreements were obtained between model predictions and corresponding experimental data. The developed model was then utilized to predict the behavior of TMAFBR under various operating and design conditions. Moreover, the influences of tapered angle, bed operating temperature and pressure, and feed temperature on the methane conversion and the total yield of hydrogen were carefully investigated. Furthermore, the performance capability of the TMAFBR was compared with that of a columnar one under identical operating conditions. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.