Thermochemical cycles for production of hydrogen from water can be constructed by appropriate combination of hydrogen- and oxygen-producing reactions carried out at different temperatures. While hundreds of specific reaction schemes are possible, the individual reactions can be regarded as belonging to relatively few general types. On the basis of published thermochemical. data, we describe a procedure whereby an equilibrium analysis of these reaction types can be carried out systematically for a large number of specific sets of reactants. This provides quantitative criteria for assessing the inherent thermodynamic viability of possible reaction cycles, which may be of use when coupled with the more practical considerations that have traditionally formed the basis for the design of thermochemical hydrogen-production schemes. Results of applying this thermodynamic screening process systematically to hydrogen production reactions involving a large number of metal-metal oxide and metal-metal oxide-carbon systems show that polythermal reaction schemes involving the latter systems are highly efficient in generating hydrogen from coal, in comparison with usual coal gasification processes.