Residual stresses in a stack of the anode-supported planar SOFC were measured by the X-ray diffraction method (the sin(2)psi method). The stack used for the stress measurements was composed of a single cell and separators of an alloy. In this measurement, the residual stresses in the electrolyte under the alloy separator and the cathode were focused on. In order to detect the diffraction from the electrolyte under the separator or the cathode, an X-ray energy of 38.8 keV was selected. For the stress measurement, a diffraction peak of YSZ(711) plane was used. A synchrotron radiation was employed as an excellent X-ray radiation for precise stress measurements. In addition to the stress measurements, numerical simulations for the residual stresses in the cell stack were carried out. (C) 2004 Elsevier B.V. All rights reserved.