A mathematical model for PSA separation of n/iso-paraffins has been developed. A cycle described in patent literature (Minkkinen et al., US Patent 5,233,201, 1993) was simulated. Model parameters (equilibrium isotherms and kinetic parameters) were found from independent experiments in our laboratory and from correlations available on literature (axial mass and heat dispersion; film mass and heat transfer). Isothermal and adiabatic cases are studied. Simulated results were consistent with patent data. The effects of temperature, feed pressure and feed flowrate on process performance are addressed. Lower performances are obtained by decreasing temperature, feed pressure and by increasing feed flowrate.