Abstract: A process and apparatus for producing a carbon monoxide-containing product from a feed containing hydrogen, carbon monoxide, methane, nitrogen and optionally argon. The carbon monoxide-containing product is produced using a hydrogen stripping column for forming a hydrogen-enriched vapor and a hydrogen-freed liquid, a nitrogen separation fractionator for forming a nitrogen-enriched vapor and a nitrogen-depleted liquid containing carbon monoxide and methane from the hydrogen-freed liquid, and a carbon monoxide/methane separation fractionator for forming the carbon monoxide containing product and a methane-enriched liquid from the nitrogen-depleted liquid. At least part of the nitrogen separation fractionator condenser duty provides the feed vaporization duty and reboiler duty for the carbon monoxide/methane separation fractionator, thereby reducing the energy requirement for the separation.