The proposing team has recently obtained important neutron scattering results on samples of different kind of ice containing molecular hydrogen (sII and sH hydrogen-filled clathrate hydrates), measured on TOSCA, disclosing the quantum dynamics of the guest H2 molecules inside the host cages. This proposal aims to study HD molecules filling the newly discovered ice XVII, still formed by molecular hydrogen and water, but having a different crystal structure than clathrate hydrates. This system, due to its high porosity and fast hydrogen release, might have a relevance for hydrogen storage applications. The molecular cross section of HD, in contrast with that of para-H2, is such that both the centre-of-mass and rotational bands will appear with marked intensity in the spectrum.