The hydration behavior of synthetic magadiite exchanged with H+, Na+, K+, Mg2+, and Ca2+ was investigated by combining thermal analyses, water adsorption gravimetry, X-ray diffraction, and spectroscopic techniques, including Si-29 NMR, infrared, and Raman under various pressures. Thermal analyses reveal distinct water populations, the number of which depends on the valency of the cation. Except for H-magadiite, which does not swell, water adsorption isotherms exhibit two steps, corresponding to two increases of the interlayer distance. These phenomena are shifted toward higher, relative pressures in the case of divalent exchanged samples. For Na- and K-magadiite, the adsorption of the first water molecules generates a water molecule in a C, symmetry, interacting simultaneously with both the cation and the surface. For higher relative pressure, two new populations of water molecules appear: (i) water molecules linked to the cation and (ii) doubly hydrogen-bonded molecules. In the case of Mg2+, the first hydration step is much less clearly defined and spectroscopic analyses suggest the simultaneous existence of water molecules in C-1 symmetry and linked to the magnesium cations. Finally, when calcium ions are exchanged in the interlayer space, they interact strongly with SiO- groups and water/cation interactions are not strong enough for displacing Ca2+ from its initial position. For this reason, no water molecules in C-1 symmetry develop and only water molecules linked to,the cation are observed at first. For higher relative pressures, liquidlike water molecules are present, in the intragallery space but no doubly hydrogen-bonded network develops.