Development has been initiated on a three-reaction, hybrid thermochemical-electrolytic process for splitting water into hydrogen and oxygen. This process can be run at 500 degrees C, making it suitable for linking to nuclear reactors that run colder than the very highest temperature gas cooled reactors. This feature also makes the materials requirements less stringent than for high temperature cycles, many of which require temperatures in the range of 800-900 degrees C. The process consists of three reactions-two thermochemical and one electrolytic. The themochemical reactions sum to the reverse Deacon reaction. The electrolytic step involves the electrolysis of anhydrous HCl. The estimated energy savings for this process relative to electrolysis of water are in the vicinity of 15%, due to the low energy requirements of anhydrous HCl electrolysis. Preliminary experimental results indicate that a silicalite-supported catalyst for the reverse Deacon reaction has the potential of promoting fast reaction kinetics and long-term stability of the solids. Published by Elsevier Ltd on behalf of the International Association for Hydrogen Energy.