This paper presents a technology for producing high purity hydrogen by using supported palladium (Pd) membrane. The membrane is prepared by electroless plating and is stable among 300-400 degreesC. The membrane shows high permselectivity in range of 200-1400 for H-2/N-2 and hydrogen permeance of 3-7 m(3)/m(2)-h-atmo(0.5). A mathematical model describing separation behaviour of membrane tube is used to predict the permeation parameters. Accordingly, the hydrogen flux and recovery yield can be calculated as the hydrogen is recovered from the recycle gas of catalytic reformer in refinery operation. A self-heating hydrogen separator containing ten membrane tubes was field-tested for the separation and purification of hydrogen. The supported Pd membranes show very good stability under the real environment of the gas mixture out of catalytic reformer. The total time on stream for the operation was more than 1000 h. The permeated hydrogen flux mainly depends on the pressure and flow rate of feedstock. The higher the pressure and feeding rate, the higher the hydrogen flux. However, the recovery yield of hydrogen decreased with increasing feeding rate. For instance, at the load-to-surface ratio of 4 m(3)/h-m(2), a recovery yield of near 90% could be obtained. As the ratio increased to 8 m(3)/h-m(2), the recovery yield decreased to about 70%. The purity of hydrogen can be raised from around 82 to 99.6% or above, which is apparently higher than those separated by polymeric membranes.