The present invention provides for a process for producing carbon monoxide. A feed gas stream of hydrogen, carbon monoxide and carbon dioxide is directed to a membrane unit which separates the feed gas stream into two streams. The stream containing carbon monoxide is directed to second membrane unit for further purification and the steam containing the carbon dioxide and hydrogen is fed to a reverse shift reactor to produce more carbon monoxide. The carbon monoxide recovered from the reverse shift reactor is purified in a third membrane unit and directed back to the first membrane unit and is further purified and recovered as additional carbon monoxide product.