Abstract: Complexes formed by straight chain, primary, aliphatic alcohols from methanol to n-decanol with Ca- and Na-montmorillonite from the liquid and vapour phases, have been investigated by X-ray techniques. Satisfactory complexes are formed more readily by the Ca-mineral and from the liquid phase rather than from the vapour phase. Molecular configurations of the adsorbed molecules are suggested consistent with the experimental data. The importance of cation-dipole interactions for the lower members of the series is stressed.