Graphene-based materials have unique structural and physiochemical properties, and have been exhibited as efficient working substances to filter salts in saline water. Understanding the microscopic nature of how water molecules move on the graphene surface is of both of scientific and practical importance, and unfortunately this knowledge is largely lacking. Neutron scattering is the appropriate tool to study the dynamics of surface water, and has been used extensively to study the effect of confinement in porous silica and carbon nanotubes,as well as hydration water on protein surfaces. Here, we propose to use neutron spectroscopy to study how water moves on the surface of graphene.