In this paper we show a new application of the atomic layer epitaxy technique to prepare binary alloy nanoparticle catalysts on various supports. The technique is used to prepare Cu/Pd bimetallic catalysts on SiO2 and on gamma-Al2O3. The samples were characterized by means of transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS) measurements. The EXAFS results show alloying in the Cu/Pd samples with a Cu-rich surface for the alumina-supported sample and random alloying for the silica-supported sample. From TEM and EXAFS measurements the particle sizes are determined to be in the range 20-60 Angstrom.