Polyethylenimine (PEI)/poly(vinyl alcohol) (PVA) blend membranes were prepared for the facilitated transport of CO2. The polymeric carrier PEI was retained in the bland membrane by the entanglement with PVA chains. The CO2 permeance decreased with an increase in CO2 partial pressure in feed gas, whereas the N-2 permeance was nearly constant. This result clearly showed that only CO2 was transported by the facilitated transport mechanism. The CO2 and N-2 permeabilities increased monotonically with the PEI weight percent in the blend membrane, whereas the selectivity of CO2 over N-2 showed a maximum. The selectivity increased remarkably with increasing heat-treatment temperature of the membrane. The highest selectivity obtained reached more than 230 when the CO2 partial pressure was 0.065 atm. The prepared membrane was stable.