The strain in epitaxial tnultilayers with coherent interfaces between yttria stabilized zirconia and rare earth metal oxides is investigated as a function of the layer thickness. An analytic model was developed to describe the strain, which is analyzed by measuring distinct XRD reflections in two orientations. Applying our model to this data the interface thicknes delta(0) is estimated. For Y2O3/YSZ multilayers delta(0) is 9.3 nm and for Er2O3/YSZ multilayers delta(0) is 82 nm. Our findings are in accordance with the assumption that mismatch induced stress can be relaxed by elastic deformation. (C) 2014 Elsevier B.V. All rights reserved.