The Selective Surface Flow (SSF) membrane, consisting of a nanoporous carbon layer supported on a macroporous alumina tube, can be used to enrich hydrogen from a feed gas containing hydrogen and hydrocarbon mixtures. The membrane produces a hydrogen-enriched product stream at feed gas pressure by selectively rejecting the hydrocarbons to the low pressure side of the membrane. Bench-scale testing of the membrane showed that very high rejections of C-2(+) hydrocarbons can be achieved from a feed gas containing low concentrations of hydrogen at moderate pressure. The membrane has been scaled-up in length and field-tested in modular form using a real refinery waste gas under actual operating conditions. It successfully tracked the performance of the bench-scale unit under field conditions. Both bench-scale and field-scale performance data are described. Six months of continuous operation in the field did not exhibit any degradation of membrane performance.