Amorphous metal alloys with the compositions (at.%) Au5FeZr14 and Au5AgZr14 have been used as precursors for the preparation of gold-zirconia-iron oxide and gold-silver-zirconia catalysts for low-temperature CO oxidation. The catalysts were prepared by in situ activation (oxidation) of the glassy metal alloys under CO oxidation conditions at 280 degrees C. The structural and chemical changes occurring during the transformation of the precursor alloys to the active stable catalysts were followed by thermal analysis, X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. When exposed to CO reaction conditions, the glassy metal alloys exhibited initially very little activity due to the very low surface area of the alloys (<0.02 m(2)/g). The activity developed with time on stream reaching a steady state after complete oxidation of the alloys. The stable active catalyst derived from Au5FeZr14 was made up of gold particles supported on zirconia in which the iron oxide was dispersed. The catalyst prepared from Au5AgZr14 contained gold-silver particles supported on zirconia. The zirconia formed by oxidation of the zirconium constituent was present in both catalysts as a mixture of poorly crystalline monoclinic and tetragonal phases. Both catalysts were microporous with BET surface areas of 30 m(2)/g (Au5FeZr14) and 45 m(2)/g (Au5AgZr14). Kinetic tests performed in a continuous tubular microreactor in the temperature range from -20 to 50 degrees C showed that both catalysts are highly active for CO oxidation at low temperature. CO oxidation rates increased considerably if the CO:O-2 ratio in the reactant feed was changed from stoichiometry (2:1) to conditions of excess oxygen (1:2).