Syngas operations require separation of CO2 and hydrogen for hydrogen production at refineries and petrochemical plants, and potentially for combined hydrogen production and CO2 capture at integrated gasification combined cycle (IGCC) power plants. Membranes that selectively permeate CO2 have attracted significant interest, because the purified hydrogen is retained at high pressure, thus avoiding costly downstream recompression. In this work, Polaris (TM) thin film composite membranes were evaluated for CO2 removal from syngas: these membranes are highly permeable to CO2 and reject the other major components of syngas, including hydrogen, carbon monoxide and methane. Part I of this study describes the three-stage development of Polaris membranes for CO2/H-2 separation, including: laboratory parametric tests of membrane stamps using pure- and mixed-gas streams, pilot-scale tests of membrane modules using real syngas at a coal-fired gasification plant, and field demonstration of a membrane system producing liquid CO2. The gasification plant where the field tests were conducted is at the National Carbon Capture Center (NCCC) in Wilsonville, AL The membrane demonstration system processed 227 kg/h of syngas (equivalent to a 0.15 MWe IGCC power plant) containing similar to 9% CO2, and produced a liquid CO2 stream containing 95+% CO2. Part II of this study will explore the potential opportunities for the use of CO2-selective membranes in commercial hydrogen purification and CO2 capture, including the results of techno-economic analyses for various process designs.