Abstract: An endothermic gas generator having separate sources of oxygen and hydrocarbon gas at pressures above the pressure of the endothermic gas to be produced, the sources of oxygen and hydrocarbon gas being interconnected through separate pressure reducing valves and to a gas tight reaction chamber, the reaction chamber containing catalyst bodies and being heated to a temperature sufficient to support a reaction between carbon atoms and oxygen atoms to produce an endothermic gas, the reaction chamber having a outlet port for an endothermic gas resulting from the reaction of the oxygen and the hydrocarbon gases at a pressure approximately that of the mixture of gases entering the reaction chamber.