NOVELTY - Producing hydrogen (81) from a gas stream comprising hydrogen sulfide (80) or hydrogen sulfide and carbon dioxide, comprises: e.g. passing the gas stream to a vertical reactor chamber (51), where the reactor chamber has an outer cylindrical wall defining an interior chamber including a heating zone, a membrane and a sulfur condenser; reacting the hydrogen sulfide and optionally the hydrogen sulfide and the carbon dioxide in the heating zone at 400-700 degrees C, and optionally water in the interior chamber; and continuously and immediately removing the hydrogen gas through the membrane.    USE - The process is useful for producing hydrogen (claimed) which is used as fuel in transportation industries.    ADVANTAGE - The process converts at least 99.9% of hydrogen sulfide (claimed), and provides the gas with no detectable hydrogen sulfide (less than 4.7 ppb) and sulfur.    DETAILED DESCRIPTION - Producing hydrogen (81) from a gas stream comprising hydrogen sulfide (80) or hydrogen sulfide and carbon dioxide, comprises: passing the gas stream to a vertical reactor chamber (51), where the reactor chamber has an outer cylindrical wall defining an interior chamber including a heating zone, a membrane and a sulfur condenser, and the reactor has (a1) an inlet for introducing the gas stream into the interior chamber, (a2) the heating zone disposed in the interior chamber and adapted to contact the gas stream, where the heating zone comprises a catalyst comprising azurite, malachite or a metal having 75% of nickel and 25% of chromium, (a3) the membrane comprising a ceramic membrane disposed in the interior chamber, where the ceramic membrane is permeable to hydrogen gas but impermeable to hydrogen sulfide and sulfur vapor, and the membrane interior defines a flow passageway in communication with a first outlet, (a4) the sulfur condenser being disposed in the interior chamber below the membrane in fluid communication with a second outlet, and (a5) a gas outlet in communication with the interior chamber; reacting the hydrogen sulfide and optionally the hydrogen sulfide and the carbon dioxide in the heating zone at 400-700 degrees C where a conversion of hydrogen sulfide is at least 95% to provide hydrogen gas and sulfur vapor, and optionally water in the interior chamber; continuously and immediately removing the hydrogen gas through the membrane to provide hydrogen and withdrawing the hydrogen from the first outlet; continuously condensing the sulfur vapor in the condensing zone to provide liquid sulfur withdrawing the liquid sulfur from the second outlet; and withdrawing a reactor effluent gas from the interior chamber from the gas outlet, where the reactor effluent gas is free of hydrogen sulfide and sulfur. An INDEPENDENT CLAIM is also included for a reactor for the continuous and essentially complete conversion of hydrogen sulfide to hydrogen gas and liquid sulfur in a single vertical reactor chamber, where reactor chamber has an outer cylindrical wall defining the interior chamber, and the components (a1)-(a5) as above per se.    DESCRIPTION OF DRAWING(S) - The figure shows a perspective view of the reactor.    Reactor chamber (51)    Catalyst coated heated area (52)    Nichrome wire (61)    Hydrogen sulfide (80)    Hydrogen (81)