This paper proposes a retention model which predicts that the displacement of non-polar solutes from a revesed-phase chromatographic column is accompanied by the adsortion of a stoichiometric number (Z) of solvent molecules. The number contact surface areas. Incerasing solute contact surface area would increase Z whereas increasing solvent contact surface area presented are consistent with this model. Further predictions of the model are that (1) plots of log k' versus the inverse log of solvent concentration will be non-linear at solvent concentrations where the surface of a reversed-phase support is not fully solvated, and (2) only a portion of a reversed-phase support. Non-linearity in plost of log k' versus the inverse log of solvent concentration was in fact observed at solvent concentrations where solvation of the reversed-phase support is incomplete.