In collaboration between the Forschungszentrum Jülich (FZJ) and the Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II) a single crystal diffractometer optimised for crystals with large unit cells is being built. Its scientific focus will be the determination of the exact location and bonding properties of hydrogen atoms in protein or DNA crystals. With this information the hydration pattern of proteins can be studied, the protonation state of critical amino acid side chains can be determined and even dynamical information can be obtained by determining the hydrogendeuterium exchange of the protein backbone. In order to achieve these results two detector concepts are foreseen: a) an image plate detector covering a large solid angle and b) a neutron scintillator imaged onto a CCD-camera providing a fast read out for a timely alignment of the crystals and additional detection abilities.