Novel supported polymeric liquid (SPL) membranes have been prepared and shown to be applicable for the separation of CO2 from mixtures with N-2 at the elevated temperature encountered in flue gas. The membranes were fabricated by immobilizing polystyrene, polyethylene, and polydimethylsiloxane into the pores of borosilicate glass supports. At 250 degrees C, the CO2 permeability and CO2/N-2 separation factors were 3000-9000 barrer and 1.7-3.7, respectively. It was shown that polymers which have a lower T-g or melting temperature than the operating temperature can be used as SPL membrane materials at elevated temperatures.