Solid Oxide Fuel Cells (SOFCs), known for their high (up to 80%) chemical to electrical/thermal conversion efficiencies, their versatility in fuel intake (hydrogen, natural gas, methanol and other petroleum products etc.) and their relatively environmentally benign operation, have a high market potential, but are not yet mass produced, because of outstanding technological and economic issues.This proposed project aims to address these problems by establishing the feasibility of, and developing, a novel design of SOFC, fabricated using hollow fibres, thereby increasing the specific surface area of electrodes, increasing the power output per unit volume/mass, facilitating sealing at high temperatures, and decreasing costs. The electrolyte in the hollow fibre configuration will be fabricated firstly by a combined phase inversion/sintering technique and consists of a thin dense layer, with integrated porous sub-layers on both sides. The porous sub-layers will then be deposited with anode and cathode materials, to produce a single hollow fibre SOFC, bundles of which will be assembled subsequently into a SOFC stack. The performance of both single cells and SOFC stacks will be investigated as a function of the fabrication and operational parameters. Initially, yttrium-stabilised zirconia (YSZ) will be used as the electrolyte, as the feasibility of producing this in fibre form has already been established, though not yet at the targeted electrolyte thickness of < 10 micron and with the required structure; to decrease operating temperatures from ca. 900 to 500-750 C, Ce0.9Gd0.1O1.95 (CGO) electrolyte will be used subsequently. As this proposal is concerned with establishing feasibility of the reactor design concept, hydrogen will be used as a model fuel at Ni anodes, coupled to oxygen reduction at La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathodes; reactor performance with other fuels would be part of a subsequent project proposal.