A composite material composed of 60 vol.% Bi1.6Y0.4O3 and 40 vol.% Ag was directly fabricated by a citrate sol-gel method. Composite material constituting of metallic Ag and bismuth oxide phase with a high oxide ionic conductivity was formed by heating the precursor above 1073 K. A well-sintered material was fabricated using the precursor powder prepared via the sol-gel route. Oxygen permeation in the Bi1.6Y0.4O3-Ag composite was measured as a function of the partial pressure difference of oxygen between the two sides of a membrane and temperature. The rate-determining step in oxygen permeation is concluded to be oxide ion transport in the Bi1.6Y0.4O3 component of the composite. (C) 2004 Elsevier B.V. All rights reserved.