TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The catalyst comprises 0.01-6 wt.% (preferably 0.1-4 wt.%) iridium. It may contain another metal that exhibits catalytic activity, e.g. nickel, cobalt, and/or ruthenium. The catalyst support comprises greater than or equal to 95 vol.% (preferably greater than or equal to 98 vol.%) monoclinic zirconia or greater than or equal to 98 vol.% alkaline-earth metal hexaaluminate. Preferred Components: The iridium is uniformly dispersed on the catalyst support. The catalyst support has an inner region and an outer region surrounding the inner region. The outer region comprises more iridium than the inner region. The alkaline-earth metal hexaaluminate comprises alkaline-earth metal(s), e.g. calcium, strontium, or barium. The alkaline-earth metal hexaaluminate is BaO.6Al2O3. The precursor oxide comprises alkaline-earth metal oxide. Preferred Properties: The catalyst support has a surface area of greater than or equal to 12 m2/g (preferably greater than or equal to 18 m2/g). Preferred Gas: The inert gas is helium, neon, argon, krypton, xenon, or nitrogen. The atmosphere contains greater than or equal to 50 vol.% nitrogen. Preferred Method: The precursor oxides are heated in an atmosphere having oxygen partial pressure of less than or equal to 0.10 atm at not greater than 1100degreesC (preferably not greater than 800degreesC). Heating is performed at a total pressure of less than, greater than, or equal to 1 atm. The method includes heating the precursor oxide in another atmosphere (preferably air) having an oxygen partial pressure of greater than 0.20 atm and a total pressure of 1 atm. Each heating step may be repeated more than once.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The catalyst comprises 0.01-6 wt.% (preferably 0.1-4 wt.%) iridium. It may contain another metal that exhibits catalytic activity, e.g. nickel, cobalt, and/or ruthenium. The catalyst support comprises greater than or equal to 95 vol.% (preferably greater than or equal to 98 vol.%) monoclinic zirconia or greater than or equal to 98 vol.% alkaline-earth metal hexaaluminate. Preferred Components: The iridium is uniformly dispersed on the catalyst support. The catalyst support has an inner region and an outer region surrounding the inner region. The outer region comprises more iridium than the inner region. The alkaline-earth metal hexaaluminate comprises alkaline-earth metal(s), e.g. calcium, strontium, or barium. The alkaline-earth metal hexaaluminate is BaO.6Al2O3. The precursor oxide comprises alkaline-earth metal oxide. Preferred Properties: The catalyst support has a surface area of greater than or equal to 12 m2/g (preferably greater than or equal to 18 m2/g). Preferred Gas: The inert gas is helium, neon, argon, krypton, xenon, or nitrogen. The atmosphere contains greater than or equal to 50 vol.% nitrogen. Preferred Method: The precursor oxides are heated in an atmosphere having oxygen partial pressure of less than or equal to 0.10 atm at not greater than 1100degreesC (preferably not greater than 800degreesC). Heating is performed at a total pressure of less than, greater than, or equal to 1 atm. The method includes heating the precursor oxide in another atmosphere (preferably air) having an oxygen partial pressure of greater than 0.20 atm and a total pressure of 1 atm. Each heating step may be repeated more than once.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The active feedstream comprises greater than or equal to 10 ppm (preferably greater than or equal to 100 ppm) sulfur. It may contain greater than or equal to 100 ppm oxygen. Preferred Components: The gaseous hydrocarbon comprises methane, ethane, propane, and/or butane. Preferred Method: The method includes passing an inactive feedstream comprising air and/or gaseous water, less than 100 ppm gaseous hydrocarbon, and greater than or equal to 100 ppm or greater than or equal to 1 vol.% oxygen, over the catalyst. Each of the active and inactive feedstreams is passed over the catalyst more than once. EXAMPLE - A catalyst was prepared by impregnating iridium (4 wt.%) on pure monoclinic zirconia support. The metal was deposited from an aqueous solution of hexachloroiridic acid. After the support was impregnated with the metal-containing solution, the catalyst was dried at 110degreesC for 24 hours and calcined in air at 500degreesC. The second catalyst was aged for 11 days on a hydrocarbon feed containing sulfur and oxygen at a steam-to-carbon molar ratio of 4 and at an average temperature of 750degreesC. The catalyst showed superior activity.