Positively polarized silver nanoparticles by poly(vinyl pyrrolidone) (PVP) have been demonstrated for use as stable olefin carriers for facilitated olefin transport membranes. The formation and size of silver nanoparticles stabilized by PVP were monitored using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Nanocomposite membranes consisting of polymer and silver nanoparticles stabilized by PVP exhibited the high separation performance for olefin/paraffin mixtures. X-ray photoelectron spectroscopy (XPS) showed that silver nanoparticles stabilized by PVP exhibited a high positive polarity, resulting in the reversible interaction between the surface of silver nanoparticles and olefin molecules. (C) 2010 Elsevier Inc. All rights reserved.