The hydrogenation behavior of the intermetallic compound Dy 5 Pd 2 was investigated by means of ex situ X-ray powder diffraction, in situ neutron powder diffraction and in situ differential scanning calorimetry. The structural model of Dy 5 Pd 2 with a palladium atom at the 32(e) position x, x, x (x≈0.22, 7/8 occupation) and a dysprosium atom at almost the same location (x≈0.18, 1/8 occupation) is confirmed. Upon heating the latter approaches x(Pd) and at T=399K both positional parameters are indistinguishable. Dy 5 Pd 2 does not incorporate hydrogen (deuterium) into its crystal structure, however, starting at T=495K reacts with hydrogen to non stoichiometric dysprosium dideuteride, DyD 2+x , following a parabolic rate law. In situ differential scanning calorimetry at various hydrogen pressures up to 2.5MPa shows strongly exothermic signals, whose temperature onset depend on the gas pressure, corresponding to the formation of a mainly ionic hydride (DyH 2+x ).