Neutron crystallography has had an important but relatively small role in structural (glyco)-biology over the past years. Knowing precisely where hydrogen particles are found and how they are moved between bio-macromolecules, dissolvable atoms and substrates is a piece of the full comprehension of numerous natural structures and processes. Neutron crystallography is a powerful technique for locating hydrogen atoms and yield information on the nature of bond involving hydrogen, as well as identifying water molecules. Neutron crystallography can also be used to identify hydrogen atoms that have been exchanged with deuterium and the subsequent extend of the exchange. This provides ways to identify isotopically labeled structural features and for characterizing solvent accessibility and macromolecular dynamics, thereby offering a complementary tool to NMR methods.