Post-combustion carbon dioxide capture from power plant flue gas can play an important role in addressing current CO2 emission concerns. Air Liquide is developing a sub-ambient membrane process to remove CO2 from flue gas by careful process engineering and heat integration. We have successfully validated enhanced low temperature membrane performance reported by Air Liquide using Matrimid (R) 5218. Asymmetric hollow fiber membranes with a CO2/N-2 selectivity of 209 and CO2 permeance of 227 GPU at -50 degrees C have been fabricated. The CO2/N-2 mixed gas transport properties at -20 degrees C, -30 degrees C, -40 degrees C and -50 degrees C are measured in an effort to better understand fundamentals of the enhanced low temperature performance. The permeance of CO2 is minimally affected by temperature while comparatively large increases in CO2/N-2 selectivity are observed. The permeance of CO2 increases with increasing pressure while minimal changes in CO2/N-2 selectivity are observed. High productivity and high selectivity are achievable with laboratory spun Matrimid (R) hollow fibers. A hypothesis regarding the fiber's fused-nodular skin morphology is proposed and supported by confirmatory experiments. (C) 2014 Elsevier B.V. All rights reserved.