We propose to study the hydration of N-methylacetamide (NMA) at ambient conditions and at two concentrations, namely 1 NMA : 50 H2O and 1 NMA : 15 H2O, by applying the isotopic H/D substitution on SANDALS. The rational behind this experiment is twofold: - at the lowest concentration, we want to compare the hydration shell of the two otherwise identical methyl groups, attached to the carbonyl carbon and to the amide nitrogen atoms, respectively. ¿ at the highest concentration, we want to study the NMA association.