In our quest to generate novel drug delivery systems, we have synthesised two novel, non-toxic inorganic systems in form of hydroxy couble salts (HDSs) from biocompatiple divalent metals. The new HDSs showed remarkable drug release profile in conditions that mimic passage through the human gastrointestinal tract. Whilst the metal positions could be determined in both the tetrahedral and octahedral positions, the position of the chloride counterion and more importantly the H atom positions are not clear. We thus propose to refine the crystal structures of the new HDSs from neutron diffraction data collected on POLARIS, which will allow the precise location of H atoms and resolving the counterion position. This will enable us to run molecular dynamics simulations for the prediction and improvement of drug release from HDSs under simulated physiological conditions.