Membrane-based separation of olefin-paraffin mixtures and the subsequent scaling-up of the process is gaining a lot of importance in today＇s chemical and petrochemical industry. The performance of polymeric membranes made of poly (phenylene oxide), polysulfone, cellulose acetate and ethylcellulose was investigated for the separation of propylene from propane. Ethylcellulose was found to have good potential for recovering propylene from propane-propylene mixtures commercially. The performance of single stage permeators equipped with ethylcellulose membrane was simulated by comparing mathematical models available in literature for counter-current and cocurrent flow patterns. The derivations were cast in a form suitable for computer calculation. The permeate compositions and the membrane area requirements were determined as functions of stage cut, stage pressure ratio and feed composition. A study of multistage cascade calculation for obtaining propylene of polymer grade purity has been presented for the two flow patterns. The performances of all the membranes were simulated and compared for single stage separation for countercurrent flow pattern. Comprehensive characterisation of polymeric membranes through experimental studies was essential to suggest the most optimum configuration of commercial separation system.