The effects influencing chromatographic separation of mixed electrolyte solutions with non-ionic nanoporous adsorbents have been studied by means of equilibrium sorption and break-through data measured for HCl and CaCl2. The equilibrium sorption is described using a thermodynamic model including mixing and size-exclusion effects. Models based on various assumptions are tested against experimental data measured with pure and mixed solutions on hypercrosslinked polystyrene. The equilibrium sorption of HCl and CaCl2 from pure and mixed solutions can be correlated satisfactorily, if both the size-exclusion and the activity coefficients in the pore solution are taken into account. When used in a dynamic column simulation model, the same parameters also give a reasonably good agreement with the experimental break-through curves of pure and mixed solutions. The model predictions are discussed by comparing with the results obtained using simpler models. (c) 2007 Elsevier Ltd. All rights reserved.