Solid oxide fuel cells (SOFCs) have the highest energy efficiency among various power generators. However, SOFCs generally have problems regarding to heat stress due to the heating cycle during cell operation, especially quick start-up/shut-down and the size of SOFC systems, which limit their application use. Micro tubular SOFCs are expected to be a solution to these problems because they are considered to be robust for repeated cycling under rapid changes in cell operating temperatures. If highly dense micro tubular SOFC stacks become available, it will accelerate development of SOFC systems, as well as increase a variety of applications. Our study aims to fabricate compact and high power SOFC bundles, which are composed of tubular SOFCs with the diameter of sub-millimeters. In this study, as the first stage of the development, processing technologies of tubular SOFCs and cube shaped cathode matrices were examined. Micro tubular SOFCs were fabricated using extrusion and co-firing techniques. The tubular SOFCs were then, arranged in the cathode matrices, which were piled up to be a cube shaped bundle. Each component of the cube shaped micro tubular SOFC bundle (cube) will be discussed in detail. (c) 2006 Elsevier B.V. All rights reserved.