[en] Several Ag-Cu alloys (0-0.25 at.% Cu) were studied as potential substrates for the direct pulsed laser deposition of YBCO without intermediate buffer layer. The microstructural characteristics of films and substrates were analyzed by X-ray diffraction, Raman spectroscopy, and scanning electron microscopy, whereas the superconducting properties of the films were determined by inductive and transport methods. The properties of the YBCO films were significantly influenced by small concentrations of Cu in the substrate; YBCO films on a substrate with 0.2 at.% Cu exhibited the best superconducting properties