The operating performance of a bubbling fluidized-bed membrane reactor for generating hydrogen was investigated using Pd-Ag planar membranes and both a steam methane reforming (SMR) catalyst and an autothermal refon-ning (ATR) catalyst. The reactor was mostly operated at 500-600 degrees C and 1500-2600 kPa. A detailed parametric study showed improved overall membrane effectiveness factors and hydrogen permeation fluxes compared with previous tests. Hydrogen permeation fluxes were 4.8-12 Nm(3)/m(2) h for SMR catalyst operations and 9-18 Nm(3)/m(2) h for ATR catalyst operations, significantly higher than previous hydrogen permeation fluxes reported in the literature. The ATR catalyst led to better performance than the SMR catalyst. Some catalyst particles were lost during operation with both catalysts, while the catalyst activity was stable. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.