NOVELTY - Production of hydrogen involves reacting hydrocarbon with water and oxygen in presence of catalyst by auto thermal modification process in a reactor. The reactor (2) comprises gas feed port (3) for introducing a gas that contains hydrocarbon and oxygen, and peripheral wall (5) that forms reaction region (2a) for the hydrocarbon and oxygen in downstream of gas feed port. Water vapor for cooling peripheral wall, which is heated by reaction heat between hydrocarbon and oxygen in auto thermal modification process, is introduced into reaction region from outside of peripheral wall.    USE - Production of hydrogen used as fuel for fuel cell, and reducing agent.    ADVANTAGE - The method economically and efficiently provides hydrogen. The apparatus for producing hydrogen has improved durability and heat resistance.    DETAILED DESCRIPTION - Production of involves reacting hydrocarbon with water and oxygen in presence of catalyst by auto thermal modification process. A reactor comprises gas feed port for introducing a gas that contains hydrocarbon and oxygen, and peripheral wall that forms a reaction region for the hydrocarbon and oxygen in the downstream of the gas feed port. Water vapor for cooling the peripheral wall, which is heated by the reaction heat between the hydrocarbon and oxygen in auto thermal modification process, is introduced into the reaction region from the outside of the peripheral wall through a water vapor channel that penetrates through the inner and outer peripheral surfaces of the peripheral wall. The water vapor that has cooled the peripheral wall is used as at least some of the water vapor to be reacted with the hydrocarbon in the auto thermal modification process. An INDEPENDENT CLAIM is included for apparatus (1) for producing hydrogen.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of the apparatus for producing hydrogen.    Apparatus (1)    Reactor (2)    Reaction zone (2a)    Gas introduction port (3)    Surrounding wall (5)    Outer and inner peripheral surfaces (5a,5b)