RDE voltammetry, XPS and XRD techniques were applied to investigate the codeposition of copper and tin from acid gluconate solutions. Voltammograms contain two plateaus of limiting current of diffusive nature which obeys Levich equation. Underpotential deposition of tin occurs at potentials 0.3 V higher than the equilibrium potential of Sn vertical bar Sn(II) electrode. Cu-Sn deposits contain carbon and oxygen that prevail at the surface and are found in the deeper layers of coatings. Chemosorption of gluconic acid with its partial destruction is supposed to take place. Bright Cu-Sn coatings are obtained when the quantity of inclusions is sufficiently high. Cu-Sn coatings obtained in the UPD area consist of alpha phase or solid solution of tin in copper and a small amount of pure copper. The beta-CuSn and delta-CuSn phases as well as a small amount of eta phase were detected at -0.31 V. At a more negative potential (-0.4 V) Cu-Sn coatings contain the pure Sn phase, eta phase and a small amount of beta-CuSn. (C) 2010 Elsevier B.V. All rights reserved.