An advanced flexible solid oxide fuel cell (SOFC) stack concept with the potential for increased reliability, better performance and lower cost is being developed. This stack concept integrates prime-surface interconnects and single cells into a lightweight and compact structure with reliable gas seals for efficient operation at different temperatures depending on selected materials. The concept has several attractive features icluding reduced stack weight and volume, decreased performance losses in stacking, improved sealing, versatility in incorporation of different types of cell construction (for example, conventional sintered cells or thin-film metal supported cells) and flexibility in gas flow configuration. The prime-surface interconnect is a one-piece metal sheet that incorporates both fuel and oxidant flow fields with peaks o one side of the interconnect serving as flow channels (valleys) on the other side; for exampe, the egg-carton shaped prime-surface flow field. The design of the prime-surface interconnect including the key factors impacting on pressure drop, flow uniformity and formability is being evaluated. Hydroforming has been identified as the forming appoach for prime-surface interconnects. Development of metal-supported cells has been initiated. A fabrication process based on sputtering is being developed for producing cells on metal supports for this stack concept.