NOVELTY - A modification catalyst comprises inorganic complex oxide carrier carrying rare-earth-metal oxide and alkaline-earth metal oxide, nickel and platinum-group metal including rhodium. The inorganic complex oxide carrier contains alumina. When line-analysis measurement of rhodium is performed, ratio of characteristic-X-ray intensity of rhodium detected from the carrier outer surface with respect to characteristic-X-ray intensity of all detected rhodium by less than 10% of distance of carrier diameter is 90% or more.    USE - Modification catalyst is used for producing hydrogen using apparatus for fuel cell system (all claimed).    ADVANTAGE - The hydrogen is economically produced using the modification catalyst having high durability.    DETAILED DESCRIPTION - A modification catalyst comprises inorganic complex oxide carrier carrying rare-earth-metal oxide and alkaline-earth metal oxide, nickel and platinum-group metal. The catalyst, nickel and platinum-group metal are carried by the same carrier. The inorganic complex oxide carrier contains alumina. The nickel and the platinum-group metal are carried by same carrier. The platinum group metal includes rhodium. When line-analysis measurement of rhodium is performed in the carrier diametrical direction which passes along center of catalyst cross section with electron probe microanalyzer (EPMA), ratio of a characteristic-X-ray intensity of rhodium detected from the carrier outer surface with respect to characteristic-X-ray intensity of all detected rhodium by less than 10% of distance of carrier diameter is 90% or more, and ratio of characteristic-X-ray intensity of rhodium detected from carrier outer surface by less than 20% of distance of a carrier diameter is 95% or more. INDEPENDENT CLAIMS are included for the following:    (1) manufacture of modification catalyst, which involves baking inorganic complex oxide carrier or its precursor at 650-1200 degrees C in presence of oxygen, and then, carrying rhodium to the inorganic complex oxide carrier;    (2) production of hydrogen, which involves modifying hydrogen raw material containing hydrocarbon compound using the modification catalyst, and obtaining hydrogen; and    (3) hydrogen-producing apparatus, which has modification portion having modification catalyst, and supply portion (20) which supplies hydrogen raw material containing hydrocarbon compound, and gas containing oxygen and/or steam in modification portion. Hydrogen-containing product is obtained from the hydrogen raw material by partial-oxidation reaction, self-thermal reforming reaction and/or steam reforming reaction, preferably steam reforming reaction.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of the fuel cell system containing the modification catalyst. (Drawing includes non-English language text)    Water tank (1)    Fuel tank (3)    Desulfurizer (5)    Modifier (7)    Supply portion (20)