It is necessary to know hydrogen permeation behaviors of Pd membranes with thickness of several microns or less, which are widely used for hydrogen separation applications. In this work, dense Pd membrane with the thickness of about 2.5 mu m was successfully fabricated by microfabrication technology. Hydrogen permeation of the thin Pd membrane was investigated within the temperature range of 473-673 K using conventional gas permeation method. Hydrogen permeability of the thin Pd membrane was 50-65% of that of Pd membrane with the thickness of about 0.70 mm. Pressure exponent of permeation of the thin Pd membrane decreased from 0.86 to 0.73 when permeation temperature increased from 473 to 673 K. Grain growth was found in the thin Pd membrane after permeation. CO2 gas had apparent negative effects on the hydrogen permeation of the thin Pd membrane. It might relate to the chemisorptions of CO2 on the surface of Pd membrane. (c) 2005 Elsevier B.V. All rights reserved.