The results of stress measurements obtained by x-ray diffraction are often ambiguous and difficult to interpret. In this work both neutron and X-ray diffraction methods were used to determine the residual stresses in plasma sprayed ceramic coatings. In addition a four-point bending device was used to check the correctness of method used. The results of both methods were compared. The volume- and lattice-effective Young's modulus were calculated from applied bending stress and lattice deformation, respectively. The results obtained are discussed from the point of view of the behavior of the defective coating structure influenced by tensile and compressive loading.