Electrolytic synthesis of ammonia with a byproduct oxygen gas from water vapor and nitrogen gas was demonstrated in LiCl-KCl-CsCl melt containing 0.5 mol % Li3N at 573 K under atmospheric pressure. Water vapor reacted with nitride ions to form ammonia and oxide ions in the melt. The consumed nitride ions were supplied by the reduction of nitrogen gas at the cathode and the formed oxide ions were oxidized to oxygen gas at a boron-doped diamond anode. (c) 2007 The Electrochemical Society.