TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Arrangement: The catalyst (I) and catalyst (II) are arranged at front stage and final stage of the catalyst-packed portion, respectively. Alternately, the catalyst (I) and catalyst (II) are arranged in a mixed state. Alternately, the catalysts (I and II) are arranged in the form of layers having inner layer containing catalyst (II) and surface layer containing catalyst (I).    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Catalyst: The catalyst (I) and catalyst (II) are obtained by making a support to support noble metal(s) and bake-processing the support. The noble metal is platinum, rhodium, palladium and/or ruthenium, preferably rhodium. Amount of the noble metal element is 0.1-10 mass% per catalyst, by metal conversion.Preferred Support: The support of the catalyst (I) is aluminum oxide, zirconium oxide and/or titanium oxide, preferably aluminum oxide. The support of catalyst (II) is cerium oxide and/or cerium-zirconium complex oxide, preferably cerium oxide. The catalyst (I) and/or catalyst (II) are supported by metal-form and/or ceramic-form honey-comb monolith.Preferred Composition: The mass ratio of catalyst (I) and catalyst (II) is 1:7-7:1. The amount of noble metal of the catalyst-packed portion is 0.1-12 g/L of the packing portion. EXAMPLE - An aluminum oxide support (Brunauer Emmett Teller-specific surface area of 200 m2/g) was immersed in nitric acid rhodium aqueous solution (0.36 L). The support was dried and bake-processed at 500 degrees Celsius, to obtain catalyst. Subsequently, water (0.47 L) was added to the obtained catalyst and wet-ground, to obtain slurry. The slurry was applied to ceramic honey-comb monolith, dried at 120 degrees Celsius and bake-processed at 400 degrees Celsius, to obtain monolithic catalyst (I). Similarly, catalyst (II), catalyst (III) and catalyst (IV) were prepared using aluminum oxide, as support, and platinum nitric acid, ruthenium nitric acid, and palladium nitric acid, as catalyst, respectively. Similarly, catalyst (V), catalyst (VI) and catalyst (VII) were prepared using cerium oxide (support having Brunauer Emmett Teller-specific surface area of 127 m2/g), and platinum nitric acid, ruthenium nitric acid, and palladium nitrate, as catalyst. The monolithic catalyst (I) (10 mL) was packed in quartz tube (catalyst filling portion). Monolithic catalyst (II-IV) (5 mL) was packed at the front stage of the quartz tube. Monolithic catalyst (V-VII) was packed at the final stage of the quartz tube. A mixed gas of isooctane, water vapor, and air was supplied to the catalyst-packed portion and the reaction temperature was increased from 350-750 degrees Celsius. Isooctane conversion ratio of the catalyst at 587 degrees Celsius, 650 degrees Celsius and 700 degrees Celsius was found to be 88.1 %, 98.3 % and 99.8 %, respectively. Hydrogen and carbon monoxide formation ratio of the catalyst at 587 degrees Celsius, 650 degrees Celsius and 700 degrees Celsius was found to be 31 %, 39.2 % and 43.6 %, respectively.