The energy efficiency of hydrogen recovery from mixtures of CO2, H2O, and H-2 by a polymer electrolyte hydrogen pump (PEHP) has been evaluated. The PEHP pumps protons across the polymer electrolyte, producing >99.99% pure H-2 and a concentrated CO2 stream. Single stage PEHP experiments recovered 65% of the hydrogen with an energy efficiency of 50%. The energy efficiency is limited by hydrogen mass transport across the porous gas diffusion electrode. The mass transport resistance for hydrogen increases as H-2 is depleted from the CO2/H-2 mixture by the PEHP. Analysis shows that a multistage PEHP with fixed applied potential difference can recover >90% of the hydrogen with an energy efficiency of 75%, whereas a novel multistage PEHP design with a programmed voltage profile can achieve >90% energy efficiency with >98% hydrogen recovery. (C) 2010 American Institute of Chemical Engineers AIChE J, 57: 1767-1779, 2011