NOVELTY - The microreactor (100) has flow path formed on substrate (1). A catalyst formed in flow path of surface (11) of the substrate selects exothermic reaction. A catalyst formed in flow path of other surface selects endothermic reaction.    USE - For use as modifier in electric power generating apparatus e.g.fuel cell used in electronic device e.g. mobile phone, personal computer (PC), personal digital assistant (PDA), electronic notebook, wristwatch, digital still camera, digital camcorder, game machine and electrical household machinery, and also for chemical reaction experiment in micro region, development of medicine, development artificial organ, genome and DNA analysis tool and basic analysis tool of micro fluid engineering.    ADVANTAGE - The reaction heat produced in exothermic reaction catalyst can be directly transmitted to adjacent catalyst for endothermic reaction and so, exchange of heat can be performed efficiently.    DETAILED DESCRIPTION - The microreactor (100) has pair of lid substrates (2,3) covering several grooves on both surfaces of the substrate (1) to form flow path . The flow path at surface (11,12) of the substrate is filled with catalyst with mutually different characteristic respectively. The catalyst formed at flow path of surface (11) of substrate selects exothermic reaction and the catalyst formed at other surface (12) selects endothermic reaction. A heating unit heats inner surface of flow path with electrical energy. The exothermic and endothermic reaction of catalyst results in generation of hydrogen from mixture of carbon compound containing hydrogen, water and oxygen. An INDEPENDENT CLAIM is included for electric power generating apparatus that generates electrical energy using hydrogen produced from the reactor.    DESCRIPTION OF DRAWING(S) - The figure shows a sectional view of the microreactor.    Substrate (1)    Lid substrates (2,3)    Surfaces of substrate (11,12)    Holes (21)    Connection regions (42,62)    Microreactor (100)