Scandia stabilized zirconia (ScSZ) is a candidate new electrolyte for use at intermediate temperature solid oxide fuel cells (SOFC). ScSZ powders for membranes of SOFC were synthesized using Pechini or solid state reaction methods. The cubic-rhombohedral phase transformation and phase stability of ScSZ was investigated using XRD and DSC/TG. The appearance of the rhombohedral phase was inhibited by the addition of transition oxide (MnO2). Thermal analyses and phase compositions of the precursors and synthesized powders were performed using DSC/TG and XRD.