© 2019 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. In this study, all materials that comprised solid oxide fuel cell (SOFC) stacks were re-deigned for the low temperature operation below 873K and weight saving. For weight saving of SOFC stacks, introduction of lightweight component materials and improvement of cell performance for high current density operation are needed. In estimation of SOFC stacks for 75kW power generation, weight power density reached to 1.20 kW/kg although system weight was not taken into account. Since SOFC stack unit is heaviest parts in the system, the weight power density including system can qualify over 0.3kW/kg.