A novel series of ionic liquids containing cationic silver complexes have been synthesized via a new methodology. The essence of this methodology is to form the cations of ionic liquids through the complexation reaction of neutral organic ligands with silver ion, followed by the metathesis reaction of the resulting salts with a hydrophobic anion donor (e.g., N-lithiotrifluoromethanesulfonimide). Olefin, amide, and amine compounds have been demonstrated to be effective neutral organic ligands to use in forming these silver-based ionic liquids. These novel ionic liquids, in which silver ion is an integrated component of the corresponding cations, give rise to the efficient transport of olefins through (a) the fast molecular diffusion of the silver-olefin complexes and (b) the hopping motion of the olefin ligands among neighboring cationic silver sites. This dual-transport mechanism entails the olefin-tran sport modes of both liquid and polymer membranes, leading to significantly improved transport efficiencies and energy savings for separation of olefins from paraffins via silver complexation.