In this paper, we describe polyimide-derived carbon molecular sieve (CMS) hollow fiber membranes with CO2/CH4 separation factors similar to 60 under a supercritical (1800 psia) natural gas feed comprising 50% CO2 and 500 ppm highly condensable C-7 hydrocarbons. Long-term tests extending for 200 h proved membrane stability. Temperatures ranging from -50 to 100 degrees C were also tested, and the membrane showed attractive performance under the diverse conditions studied. With attractive and stable separation performance, the CMS hollow fiber membranes studied in this work can potentially enable next generation CO2 removal processes for challenging natural gas feeds.