Deposition technique of Pd-Ag alloy membrane on porous ceramics substrate with paste coating and electroles-plating was studied. In paste coating process, palladium and silver compounds were added into a sticky organic paste with a controlled ratio to form a coating paste. The coating paste was coated on an asymmetrical composite ceramics substrate by brush coating method. The paste was then dried and calcinated to give a porous Pd-Ag alloy membrane. This membrane was electroless-plated to deposit a porous-free Pd-Ag alloy membrane, with a thickness of about 3 μm and an Ag content of 23% (atom percent). The flux of H~2 permeation of this Pd-Ag alloy membrane was 45 cm^3(STP)cm^-^2·min^-^1 at 0.1 MPa and 300℃ . Separation factor fo H~2/He could be higher than 500. The results of the experiment show that Ag transmitted to the membrane surface during the heat treatment, and the Ag contents became constant at a given treatment temperature. The preferred treatment temperature was 700℃ .

Key words: CERAMICS, PALLADIUM ALLOYS, SILVER ALLOYS, CHEMICAL PLATING, THIN FILMS