The separation performance of binary hydrogen sulfide-hydrogen mixtures by a nanoporous carbon membrane called selective surface flow (SSF) membrane is described. The membrane selectively permeates H2S from H-2, and a H-2-enriched stream is produced at the feed-gas pressure. A two-stage embodiment of the SSF membrane is described for production of high-purity H-2 with high H-2 recovery from an equimolar H2S-H-2 feed gas. A novel protocol for operation of the two-stage membrane is needed to achieve that separation goal.