[en] In this work we present a structural analysis of La_0.75Sr_0.25MnO₃/LaNiO₃ (LSMO/LNO) superlattices, performed by X-ray diffraction spectroscopy and X-ray reflectivity. The samples were deposited by dc magnetron sputtering on single-crystalline (0 0 1) oriented SrTiO₃. The strain relaxation and the roughness at the interfaces were estimated from the analysis of the X-ray patterns. The thickness of LSMO reference layers has been measured by means of low-angle X-ray reflectivity, finding a very good agreement with the nominal values