Methods for the preparation of nanosized alloys from noble metals by decomposition of monomolecular precursors are described, and the results of these studies are reported. Other aspects of the synthesis procedure and properties of bimetallic nanostructures are also considered. Thermolysis of noble metal compounds led to the formation of an ultradisperse powder of their alloys. This method affords catalysts with a uniform distribution of active particles. Nanosized particles of a number of alloys in hydrogen and inert media were prepared. The optimum parameters of the reduction of complex compounds (gas medium, thermolysis temperature, heating rate, and annealing time) were determined to obtain ultradisperse powders with the required particle size, phase composition, and structure. For Co-Pt and Pt-Pd systems, bimetallic catalysts deposited on γ-Al2O3 and Sibunit can be obtained; these catalysts show higher activity in selective oxidation of CO compared with monometallic catalysts.