TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - The catalysts capable of selectively oxidizing carbon monoxide and differing from each other in the application temperature comprises a first catalyst for selectively oxidizing carbon monoxide, the first catalyst including a carrier and Pt acting as an active metal and supported on the carrier, and a second catalyst for selectively oxidizing carbon monoxide, the second catalyst including a carrier and an active metal consisting of at least one kind or metal selected from Pd, Ru, Rh and Ir and supported on the carrier.The carrier of the first and second catalysts for selectively oxidizing carbon monoxide is selected from Y-type zeolite, mordenite, A-type zeolite, gamma-Al2O3, anatase and a crystalline silicate having the highest to the fifth highest peaks in the powder x-ray diffraction using CuKalpha ray in the lattice spacing of 3.65/0.1A, 3.75/0.1 A, 3.85/0.1A, 10.0/0.3A and 11.2/0.3A, respectively, and having the composition of formula (1) under a dehydrated state: (1/0.8)R2O.(aM2O3.bNO.cAl2O3).ySiO2 (1),R = alkali metal or H;M = element selected from VIII group elements, rare earth elements, Ti, V, Cr, Nb, Sb and Ga;N = element(s) selected from Mg, Ca, Sr and Ba;a = 0 or more;b = 0-20;a+c = 1;y = 11-3000Each of the plurality of catalysts capable of selectively oxidizing carbon monoxide and differing from each other in the application temperature is formed of a catalyst including a carrier and an active metal consisting of at least one kind of metal selected from Pd, Ru, Rh and Ir supported on the carrier. The temperature of the gaseous mixture is 50-280 degrees C when the gaseous mixture is introduced into the catalyst bed. EXAMPLE - Water-glass No.1 (SiO2:30%) was dissolved in an amount of 5,616 g in 5,429 g of water to prepare solution A. On the other hand, dissolved in 4,175 g of water were 18.9 g of aluminum sulfate, 110 g of ferric chloride, 47.2 g of calcium acetate, 262 g of sodium chloride and 2,020 g of a concentrated hydrochloric acid to prepare solution B. These solutions A and B were supplied at predetermined rates into a container to form precipitation, and the mixture was sufficiently stirred to obtain a slurry having a pH value of 8. The slurry was charged in an amount of 20 l into an autoclave, followed by introducing 500 g of tetrapropyl ammonium bromide into the autoclave to carry out a hydrothermal synthesis at 160 degrees C for 62 hours. After the synthesis, the reaction mixture was washed with water and, then, dried, followed by sintering the mixture at 500 degrees C for 3 hours so as to obtain crystalline silicate under a dehydrated state. This crystalline silicate was dipped in a 4N NH4Cl aqueous solution maintained at 40 degrees C and the solution was kept stirred for 3 hours so as to carry out the NH4 ion exchange. After the ion exchange, the crystalline silicate was washed and, then, dried at 100 degrees C for 24 hours, followed by sintering the crystalline silicate at 400 degrees C for 3 hours so as to obtain the H-type crystalline silicate. Then, 100 pts. of the H-type crystalline silicate was impregnated with an aqueous solution of chloroplatinic acid to permit 0.4 pt wt of platinum to be supported by the crystalline silicate, followed by evaporating the solvent for the drying purpose and then performing sintering at 500 degrees C for 5 hours so as to obtain a powdery catalyst. A binder consisted of 3 parts of alumina sol. (Al2O3:10 %) and 55 parts of silica sol. (SiO2:20 parts) was added to the resultant powdery catalyst together with 200 parts of water, and the aqueous system was sufficiently stirred to prepare a slurry for wash coating. Then, a monolithic substrate made of cordierite ceramics and having 400 cell lattice meshes was dipped in the slurry. After the substrate was taken out of the slurry, the slurry attached to the substrate was blown off, followed by dying the substrate at 200 degrees C. The coating amount was 150 g per liter of the monolithic substrate, and the coated substrate constituted a honeycomb catalyst for use in the removal of carbon monoxide.