NOVELTY - A method (M1) of producing hydrogen from light hydrocarbon gas involves passing gas to light hydrocarbon gas thermal decomposition zone to produce particulate carbon and hydrogen; separating carbon particles from hydrogen by contacting particles and hydrogen with liquid sulfur to produce liquid sulfur and carbon particle suspension and hydrogen; and passing portion of liquid sulfur, carbon particle suspension and an oxygen-containing gas to combustion to produce a desired temperature in the thermal decomposition zone and produce a stream containing sulfur dioxide and carbon dioxide.    USE - For producing hydrogen from a light hydrocarbon gas or from light hydrocarbon gas stream and an acid gas stream; for producing hydrogen, sulfur, a sulfur dioxide and carbon dioxide stream and a carbon dioxide and water stream from a light hydrocarbon gas stream and an acid gas stream (claimed), where hydrogen is used as automotive fuel and in refining operations.    ADVANTAGE - The method is an improved method for the production of hydrogen using excess sulfur. The method is effective in producing hydrogen using Claus plants and hence is made available for other process requirements thereby avoiding the cost and inconvenience of importation of hydrogen into the plant.    DETAILED DESCRIPTION - A method (M1) of producing hydrogen from a light hydrocarbon gas involves passing the light hydrocarbon gas to a light hydrocarbon gas thermal decomposition zone to produce particulate carbon and hydrogen; separating the carbon particles from the hydrogen by contacting the carbon particles and the hydrogen with liquid sulfur to produce a liquid sulfur and carbon particle suspension and hydrogen; and passing a portion of the liquid sulfur and carbon particle suspension and an oxygen-containing gas to combustion to produce a desired temperature in the thermal decomposition zone and produce a stream containing sulfur dioxide and carbon dioxide. INDEPENDENT CLAIMS are included for the following:    (1) a method (M2) for producing hydrogen from a light hydrocarbon gas stream and an acid gas stream involving passing the light hydrocarbon gas to a light hydrocarbon thermal decomposition zone to produce a particulate carbon and hydrogen; passing an acid gas stream to a Claus plant to produce a liquid sulfur stream and a carbon dioxide and water stream; passing the particulate carbon and hydrogen stream into contact with a portion of the liquid sulfur stream to produce a hydrogen stream into contact with a portion of the liquid sulfur stream to produce a hydrogen stream and a liquid sulfur and carbon particulates suspension; and combusting a portion of the liquid sulfur and carbon particles suspension with an oxygen-containing stream to produce heat for the thermal decomposition zone and a stream containing sulfur dioxide and carbon dioxide; and    (2) a method (M3) for producing hydrogen, sulfur, a sulfur dioxide and carbon dioxide stream and a carbon dioxide and water stream from a light hydrocarbon gas stream and an acid gas stream, involving: passing the light hydrocarbon gas to a light hydrocarbon gas thermal decomposition zone to produce particulate carbon and hydrogen; passing an acid gas stream to a Claus plant to produce a liquid sulfur stream and a carbon dioxide and water stream; contacting the particulate carbon and hydrogen with liquid sulfur to produce a hydrogen stream and a sulfur and particulate carbon suspension; and combusting the sulfur and particulate carbon suspension in a combustion zone to produce heat and a sulfur dioxide and carbon dioxide stream.