Thin Pd/alpha-Al2O3 hollow fiber (HF) membranes were prepared by an improved electroless plating technique. Pure gas permeation experiments showed that the membranes were defect free and had high hydrogen permeance. Feeding an equimolar mixture of H-2/N-2, the total diffusion flow rate of hydrogen through the composite membranes was measured in dependence of the total feed flow rate at the inlet of the shell/retentate chamber, of the temperature and of the total trans-membrane pressure difference. Furthermore, a mathematical model was derived to describe the hydrogen diffusion in pure and mixture gas experiments. The pure gas experiments were used to determine the membrane parameters. Applying the adapted model parameters, the fluxes of hydrogen occurring in the mixture gas experiments were simulated. The comparison between experimental and calculated data showed a very good agreement in a broad parameter range. (c) 2006 Elsevier B.V. All rights reserved.