The present invention relates to a method of producing solid carbonaceous C.sub.xH.sub.y, wherein the ratio of x:y is greater than 2.5:1, or a hydrogen-rich gas, wherein a hydrocarbon fuel is heated with limiting amounts of oxidizer to a temperature of at least about 1000.degree. C. whereby to effect incomplete combustion and pyrolytic decomposition of said hydrocarbon fuel, the carbonaceous product produced by that method, a method of combusting the gas produced by that method and reactors for performing these methods.
