Guanosine (GMP) is the ideal brick for controlled self-assembly of biocompatible materials, as it has the special ability to self-associate in water to form G-quartets (G4), and four stranded structures, termed G-quadruplexes (G4n). The details of its interaction with the solvent are unknown. For this reason we propose to study on NIMROD the hydration of GMP as a function of concentration in pure water and in KCl-water solutions. The experiment in water will be performed at two solute concentrations, in order to study the hydration of GMP monomers, at the lowest concentration, and to monitor the formation of quartets and their hydration at the highest. A third experiment will be perform after addition of KCl to the solution, in order to stabilize the G-quadruplexes and investigate their hydration. This data will complement previous SAXS results on the same sample.