Nuclear Production of Hydrogen : Fourth Information Exchange Meeting Oakbrook Illinois USA 14 16 April 2009 Hydrogen has the potential to play an important role as a sustainable and environmentally acceptable energy carrier in the 21st century. This report describes the scientific and technical challenges associated with the production of hydrogen using heat and or electricity from nuclear power plants with special emphasis on recent developments in high temperature electrolysis and the use of different chemical thermodynamic processes. Economics and market analysis as well as safety aspects of the nuclear production of hydrogen are also discussed.