Abstract: A cyclic, vapor-phase, pressure swing process for the separation of n-paraffins from a mixture with non-straight chain hydrocarbons comprises the steps of adsorption purge and desorption. Purge effluent is recycled through a bed of a 5 A molecular sieve in an adsorption stage and an effluent of reduced n-paraffin content is recovered. The bed is purged to remove surface adsorbed and interstitial matter by reducing the pressure in the bed by direct contact condensation with fresh feed introduced at or near ambient temperature. A purge effluent is recovered for recycle to stage (1). The bed is then desorbed to recover n-paraffins by further reducing the pressure in the bed.