This paper reports a measurement of residual stresses at different temperatures in plasma sprayed electrolyte thin-film on the cathode substrate of a solid oxide fuel cell. The study is carried out on a sample with bi-layer structure consisting of a thin-film of 8 mol% yttria-stabilized zirconia (8YSZ) and a Ca-doped LaMnO3 cathode substrate fabricated by Siemens' plasma spray technology. The lattice deformation is directly measured by the high-temperature X-ray diffractometry, from which the state and level of the residual stresses in the YSZ layer are further evaluated using the sin(2)psi-methodology. The results reveal that the stresses in the electrolyte film are compressive in nature and remain essentially unchanged from room temperature to 600 degrees C. Above 600 degrees C, the compressive stresses monotonically decrease with the temperature as the lattice relaxation prevails. At 1000 degrees C, the electrolyte layer is still under compression, implying good bonding and very likely low interfacial contact resistance within the structure. (C) 2010 Elsevier B.V. All rights reserved.