To protect the ceria electrolyte from reduction at the anode side, a thin film of yttria-stabilized zirconia (YSZ) is introduced as an electronic blocking layer to anode-supported gadolinia-doped ceria (GDC) electrolyte solid oxide fuel cells (SOFCs). Thin films of YSZ/GDC bilayer electrolyte are deposited onto anode substrates using a simple and cost-effective wet ceramic co-sintering process. A single cell, consisting of a YSZ (similar to 3 mu m)/GDC (similar to 7 mu m) bilayer electrolyte, a La0.8Sr0.2Co0.2Fe0.8O3-GDC composite cathode and a Ni-YSZ cermet anode is tested in humidified hydrogen and air. The cell exhibited an open-circuit voltage (OCV) of 1.05 V at 800 degrees C, compared with 0.59 V for a single cell with a 10-mu m GDC film but without a YSZ film. This indicates that the electronic conduction through the GDC electrolyte is successfully blocked by the deposited YSZ film. In spite of the desirable OCVs, the present YSZ/GDC bilayer electrolyte cell achieved a relatively low peak power density of 678 mW cm(-2) at 800 degrees C. This is attributed to severe mass transport limitations in the thick and low-porosity anode substrate at high current densities. (c) 2006 Elsevier B.V. All rights reserved.