Stainless steel-supported composite membranes with the Knudsen-dominated permeation behavior were synthesized via the dipping-rolling-freezing-fast drying (DRFF) and soaking-rolling-freezing-fast drying (SRFF) method. A dimethyl ether (DME) steam reforming was performed in a membrane reactor using the stainless steel-supported Knudsen membrane (SKM) with remarkably high permeability. The Knudsen membrane with high permeability was used to improve DME conversion and hydrogen recovery. Compared to a conventional reactor, the DME conversion was improved up to 48% and the hydrogen recovery was 37-38% in the temperature range of 250-450 degrees C. Moreover, the DME steam reforming-membrane reactor was combined with water-gas shift (WGS) reaction in the permeate side of the membrane reactor to obtain high CO removal efficiency. As a result, the CO concentrations was significantly reduced to below 20 ppm in the permeate side of the membrane reactor via the WGS reaction in the temperature range of 300-450 degrees C. (C) 2008 Elsevier B.V. All rights reserved.