Polymer electrolytes containing silver salts have gained great interest due to their effective performance in the separation of olefin/paraffin mixtures. However, they suffer from the poor long-term stability. The membrane performance of polyvinylpyrrolidone (PVP)/AgBF4 membranes was decreased with time primarily due to the reduction of silver ions to silver metal. In this study, non-ionic n-octyl beta-D-glucopyranoside (8G1) surfactant has been employed to prolong the stability of the separation performance of PVP/AgBF4 membranes. It was found that the growth rate of the silver particles became slower and the propylene permeability was maintained for much longer time when 8G1 was added into the membranes. The reduction behavior of silver ions to silver metal particles and their growth were investigated by Transmission electron microscopy (TEM), scanning electron microscope (SEM), and UV spectroscopy. (C) 2003 Elsevier Science B.V. All rights reserved.