The described invention is a process for producing hydrogen gas comprising (a) combusting sulfur (S) or hydrogen sulfide (H2S) with oxygen (O2) to obtain sulfur dioxide (SO2) and water (H2O), plus heat; (b) adding water to the product of (a) to obtain a sulfurous acid solution (H2SO3 and H2O); (c) applying electrical current to the sulfurous acid solution of (b) to obtain sulfuric acid (H2SO4) and hydrogen gas (H2); and, (d) using gas-liquid separation to separate the sulfuric acid from the hydrogen gas to obtain separated components of the sulfuric acid and the hydrogen gas; and, wherein the heat generated in (a) is used to generate at least a portion of the electricity for the electrical current of (c).