The low-temperature interaction of amorphous sulfur-rich sulfides MoS3 and MoSx (x ≈ 6) with hydrogen was studied under static and dynamic conditions using volumetric measurements, mass spectrometry, solid-state NMR spectroscopy, inelastic neutron scattering, temperature-programmed reduction (TPR), and X-ray absorption spectroscopy (XAS) at the S K and Mo K edges. It was observed that, at room temperature, hydrogen irreversibly interacts with the sulfur species of the amorphous sulfide. Interaction with hydrogen leads to opening of the S—S bonds within the structure. As a result, SH groups are formed, which are very labile and are easily transformed into molecular H2S under dynamic conditions (hydrogen flow). The total amount of absorbed hydrogen depends on the amount of S—S bonds in the amorphous sulfide, which can vary over a wide range.