The hollow fiber contained liquid membrane (HFCLM) permeation technique has been modified by using microporous fibers having a thin nonporous silicone coating to handle higher gas pressures. Separation of various CO2-N2 mixtures have been studied over a feed pressure range of 50-200 psig. Pure water and aqueous 20% diethanolamine (DEA) were used as liquid membranes. Two modes of operation, conventional polymeric membrane and sweep gas mode, were investigated. Permeator conditions studied include liquid membrane pressure higher and lower than the feed pressure. The aqueous 20% DEA resulted in significantly higher overall CO2 permeabilities and selectivity. A mathematical model was developed which included the pressure drop inside the fiber bores. Numerical simulations of the model describe the experimental results well.