The aim of our work is to use charge density analysis to gain insight into the process of binding relatively small anions by specifically designed small organic molecules. These molecules exploit intermolecular interactions in order to bind anions and our methodology is to systematically tailor the molecular configuration of the binder to understand how to control this process. We have been performing high resolution x-ray charge density analysis to gain further insight into the nature of these interactions, however a crucial question remains - what is the role of the proton in this process, does it transfer from the binder to the anion? The specific aim of this proposal is to perform single crystal neutron diffraction to accurately locate the position of hydrogen atoms within a series of urea based anion receptor complexes and use this information in charge density refinements.