We demonstrate that the energy efficiency of hydrogen production by electrochemical hydrogen pumping out of a plasma-energized mixture of water vapor and sulfur dioxide (SO2) can be greatly enhanced by raising the rector temperature above 800 degrees C. The critical elements for this reactor design include the use of a microporous ceramic configuration for the discharge region, a bipolar electrode connecting the plasma reactor with the hydrogen pump, and a solid oxide membrane as the electrolyte of the pump. The amount of hydrogen produced per 100 joules of electrical energy consumed to operate the reactor at 850 degrees C is 16 mL, which is more than twice the volume produced from the same reactor, operating at 100 degrees C. The energy efficiency is almost 75% of that for the electrolysis of an H2O/SO2 mixture. This type of plasma-assisted hydrogen pump opens up the possibility of producing hydrogen gas from water using the thermal energy from a nuclear reactor. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.