NOVELTY - Solid carbon materials (SCM) are supplied to plasma reactor chamber (34) of an arc plasma reactor to form several minute arc passages (35) in SCM. Electric power is supplied to arc discharge electrodes (36,38,40) located in chamber to produce arc discharge plasmas in passages. Steam is passed through passages so as to react with SCM in presence of discharge plasmas to produce hydrogen rich gas.    USE - To produce hydrogen from solid carbon materials and feed water, used as chemical raw material and fuel.    ADVANTAGE - Since the feed water and solid carbon material used as raw material are inexpensive, hydrogen is produced economically. Hydrogen is produced efficiently using compact arc plasma reactor having high operating performance. Since all the carbon materials are consumed only for producing hydrogen and no carbon material is used as fuel for reformer, the utilization rate of the carbon material is high and cost of producing hydrogen is reduced. Since condensed water is recycled to the arc plasma reactor, the amount of feed water used is reduced and environmental pollution is eliminated.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for hydrogen production system, which consists of the arc plasma reactor, a feed water supply pump and an alternating current power supply. The arc plasma reactor has a solid carbon supply port (12), a feed water supply port (52), and an insulating casing (32) formed with a synthesis gas outlet, arc plasma chamber formed in the insulating casing, alternating current arc discharge electrodes located in one end of the chamber, a neutral electrode (42) located in the other end of the chamber and several minute arc passages formed in solid carbon material filled in the chamber. The feed water supply pump supplies feed water into the plasma chamber through a feed water supply port to cause the feed water to be converted into steam. The alternating current power supply supplies alternating current electric power to the arc discharge electrodes to cause arc discharge plasmas to be generated in the passages, respectively, such that the water is exposed to the arc discharge plasmas to form the steam.    DESCRIPTION OF DRAWING(S) - The figure shows the enlarged cross-sectional view of the arc plasma reactor.    Solid carbon supply port (12)    Insulating casing (32)    Plasma reactor chamber (34)    Steam generating zone (34A)    Arc discharge electrodes (36,38,40)    Neutral electrode (42)    Feed water supply port (52)