TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: Catalyst (A) component contains at least one type of dual-system complex oxide of titanium and silicon, dual-system complex oxide of titanium and zirconium, and complex oxide of ternary group complex oxide containing titanium, silicon and zirconium.Preferred Method: Gas containing ammonia, organic compound and at least one type of compound chosen from sulfur oxide, hydrogen sulfide, sulfur-containing organic compound and nitrogen-containing organic compound, is oxidized and decomposed. EXAMPLE - Snowtex-20 (RTM) (in kg) (35.5) was added to 700 liters of 10 wt.% aqueous ammonia. Subsequently, 300 liters of sulfuric acid aqueous solution of titanyl sulfate was added to the mixture. The filtration wash water of the obtained gel was dried at 150 degrees C for 10 hours, and bake-processed at 500 degrees C for 6 hours. The resulting powder composition had BET surface area of 210 m2/g and titanium to silicon molar ratio of 4:1.    Subsequently, 10% monoethanolamine aqueous solution (12) containing ammonium meta-vanadate (0.56) and ammonium para-tungstate (1.79) was added to the powder composition (20). Starch was further added to the mixture, as a molding adjuvant, mixed and extruded to a shape of honeycomb structure. Subsequently, the molded product was dried and bake-processed.    The molded product was impregnated with palladium nitrate aqueous solution, dried for 3 hours at 150 degrees C and bake-processed at 450 degrees C of air atmosphere for 3 hours. The resulting catalyst had BET surface area of 130 m2/g, pore volume of 0.45 cc/g and pore diameter of 0.5 micro meters or more. Ammonia and organic compound decomposition reaction was implemented using the catalyst. The process was performed using a test gas containing 4000 ppm of ammonia, 10 ppm of acetaldehyde, 2 ppm of butyric acid, 10 ppm of hydrogen sulfide, 10% of water, 10% of oxygen and remaining of nitrogen.    The gas processed using the catalyst, had ammonia concentration of 1 ppm, nitrogen oxide (NOx) concentration of 12 ppm, acetaldehyde concentration of 0.1 ppm or less, sulfur concentration of 0.02 ppm or less and butyric acid concentration of 0.01 ppm or less.