CO2-selective membranes have a variety of applications, such as synthesis gas purification, natural gas sweetening, and greenhouse gas sequestration. In this study, CO2-selective membranes containing both mobile and fixed carriers in crosslinked poly(vinyl alcohol) were synthesized. Transport properties of membranes, including CO2 flux and permeability, H-2 flux and permeability, CO2/H-2 selectivity, and CO2/N-2 selectivity, were studied with a gas stream consisting of hydrogen, carbon dioxide, and nitrogen. The effects of feed pressure, water content, and temperature on transport properties were investigated. The membranes showed good CO2 permeabilities and CO2/H-2 selectivities up to 170 degrees C. At 120 degrees C, the CO2 permeability and CO2/H-2 selectivity reached 8200 Barters (1 Barrer = 10(-10) cm(3) (STP) cm/(cm(2) s cm Hg)) and 450, respectively. The synthesized membranes also had high CO2/CO selectivities in the temperature range of 100-170 degrees C. (c) 2006 Elsevier B.V. All rights reserved.