Brillouin scattering (BS) and X-ray absorption spectroscopy (XAS) measurements are performed on hexagonal Fe-x/Ru-y superlattices, where the iron layers adopt a hexagonal structure for thicknesses smaller than 1.4 nm. The aim of these experiments is to study the elastic properties of such a kind of superlattices and their relationship with the structure and atomic environment of the iron atoms. A clear discontinuity of 20% is observed in the surface sound velocity for Fe-12/Ru-6, this value is similar to that found in other superlattice systems. The analysis of the XAS measurements shows that there are no appreciable changes in the structure, therefore, the anomaly in the elastic constants cannot be explained as a modification in the microstructure of the layers.