We propose to study hydrogen/deuterium exchange in the new non-porous molecular solid {[Co(orotate)2(bipy)][Cu(H2O)(bipy)]}nn[Co(orotate)2(bipy)]5nH2O in order to understand the mechanism of putative proton conduction occurring in the solid. The water structure in this substance is conducive to the operation of a "Grotthuss mechanism" of proton transfer, and impedance measurements on single crystals show humidity-dependent conductivity, consistent with such a mechanism. Single crystal structure determination of an as-grown sample followed by analysis of the same sample after exposure to D2O vapor will reveal the sites subject to deuterium substitution as well as any double-well hydrogen bond paths.