Hydrogen adsorption on a Cu/MgO catalyst is investigated using in situ H-1 NMR. The adsorption is largely homogeneous, demonstrating reasonable agreement with the Langmuir isotherm and only small variations in the frequency shift and spin-lattice relaxation time with increasing coverage. The catalyst is investigated under flowing gas conditions, and the hydrogen/deuterium exchange kinetics are studied. The activation energy for exchange is measured to be 96 kJ mol(-1). The H-1 variable-temperature NMR probe developed here and used for the in situ adsorption isotherm and the flowing gas experiments is also described.