Pd-Ag alloys find technological applications in H uptake and purification. Among various peculiar properties, their electric resistivity variation as a function of the H loading features a characteristic S-shaped curve. This behaviour cannot be completely explained just by considering the well-known α-β hydride phase transformation, so the possibility of an H double-site occupancy (i.e. both octahedral and tetrahedral) has been proposed, despite its total absence in the case of the pure Pd/H system. We suggest that, similarly to the case of other double-occupancy metal hydrides, INS is one of the most suited microscopic techniques available to validate the double occupancy model, since the two distinct sites should turn out with two well separated H vibrational frequencies.we propose to measure the spectra of H absorbed in Pd/Ag using IINS on MARI at P=100kPa and 100<T<180 °C.