The invention comprises a process for obtaining a gas from a fluid fuel and an oxidising fluid, said process comprising steps in which the incoming fluid is subjected to temperature, photocatalytic action and reaction with catalysts, all this within a device with a tubular structure which the incoming fluid circulates through in a spiral manner, between a fixed bed attached to the walls of the duct and a circulating bed with an ionised gas stream that occupies a central position of the duct, producing a gas obtained.