Abstract— <p>New hybrid materials based on Ag, Cu, AgCu nanoparticles and their conjugates with quercetin were obtained using an environmentally friendly method of metal-vapor synthesis (MVS). The composition and electronic state of the nanocomposites were studied by XPS, powder X-ray diffraction, and SEM/EDX. It was found that modification of metals with flavonoid leads to stabilization of smaller particles in the conjugate compared to metal powders. Powder X-ray diffraction studies showed that the average crystallite size of metals upon introduction of quercetin decreases from 4.1 to 3.6 nm for Ag and from 8.7 to 4.8 nm for Cu. According to XPS analysis, the bimetallic composites and their conjugates consist primarily of silver in its metallic state (Ag⁰), with minor contributions from Ag⁺ and silver acetate species. Copper, however, is present in a mixture of oxidation states: Cu⁰, Cu⁺, an Cu²⁺. The data indicate that the bimetallic nanoparticles form a solid solution with a disordered structure, characterized by the presence of Ag–Cu, Ag–O–Cu, and Ag–O–Cu–O– bonds.</p>