For the practical applications of facilitated olefin transport membranes, long-term stability, high selectivity for propylene/propane, and high permeance are required. Previous results obtained for membranes consisting of poly(2-ethyl-2-oxazoline) (POZ), AgBF 4 , and Al(NO 3 ) 3 showed relatively low mixed-gas permeance, i.e., 4.8 gas permeance units (GPU), even though these membranes have excellent long-term stability. In this study, poly(ethylene oxide) (PEO) was suggested as a new polymer matrix for enhanced separation performance. When PEO was utilized as the polymer matrix, the membrane showed long-term stability and the mixed-gas permeance increased to 20 GPU. This enhanced permeance was attributed to the stabilization of silver ions in the permeable polymer matrix. The coordinative interactions in PEO/AgBF 4 /Al(NO 3 ) 3 were investigated by FT-IR, FT-Raman, and X-ray photoelectron spectroscopy analyses.