Hydrogen absorption by palladium is an issue that has been studied for decades, dueto its great importance in a future hydrogen-based economy. This is one of the most promising systems which could replace fossil fuels once these have beenexhausted. In a series of key technologies required in a hydrogen-based system, such as production, storage and hydrogen sensors, palladium is fundamental. This is due to the dissociative and absorptive properties that it possesses when it is in the presence of H2. The challenge is that still now we do not understand thése properties fully. For example, it has been reported that an alloy of Pd with just 4% of Ru drastically reduces the absorption properties of the system, although the fcc crystal structure ofPd is preserved and the concentration of Ru is very low. We believe that theunderstanding of this behavior could give important clues regarding the amazing properties of the hydrogen-palladium system, which are so important nowadays.In order to understand this phenomenon, we used three foils ofPd, Pd-Ru(4%)alloy, and Pd with a surface Pd-Ru alloy. To perform this last sample, 8 nm of Ruwere evaporated using an e-beam evaporation technique and with a heating process (up to 700°C in a high vacuum system) a surface alloy was created on one of the surfaces (top) (of ~2?m thick). The samples were characterized using Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS) and Auger Electron Spectroscopy (AES). Then, a study of the absorption properties of the foils, using Thermal Program Desorption (TPD), was performed together with measurements of the lattice parameters of the samples, using X-ray (XRD) and Grazing Incidence X-ray (GID) Diffractions techniques. As main results, a progressive reduction in the absorption properties of the samples was observed, depending on the Ru concentration presented in the alloys; a drastic reduction in the Pd-Ru(4%) sample wasfollowed by significant inhibitions of the top and then the bottom face ofthe Pd-Ru surface alloy foil. These results correlate with observed reductions in the lattice parameter of the foils, produced by the alloy. Finally, an important observation was derived from the GIDmeasurement of the Pd-Ru surface alloy sample: an intense signal corresponding to hydrogenated Pd was measured, which was not present in pure Pd. This behavior might be of technological importance because the foil can capture hydrogen even when it is exposed under atmospheric conditions (GID measurements), an effect never observed until now.PFCHA-BecasMagister en Física40p.PFCHA-BecasTERMINADA