The underpotential deposition (UPD) of silver and lead on Au(111) was performed sequentially to produce a thin composite layer. Ag was deposited underpotentially in I mM Ag2SO4 and 0.1 M H2SO4 at 0,400 V and 0.010 V vs. Ag wire. The results of cyclic voltammetry carried out on this Ag/Au(111) electrode in a Ph2+ electrolyte with 0.1 M HClO4 indicated contributions from both Au and Ag substrates. In situ STM images showed that the UPD of Pb on Ag/Au(111) had an unusual multilayer morphology. Cyclic Voltammetry was also used to demonstrate the stability and presence of the Ag adlayer in the Pb2+ electrolyte. In the presence of sodium nitrate, this composite system exhibits a catalytic effect on nitrate reduction that is not observed for Au(111), Ag/Au(111), Pb/Au(111), Ag(111), or Pb/Ag(111). Our results demonstrate that the Ag-Pb/Au(111) composite system has an enhanced catalytic effect on nitrate reduction. (c) 2005 Elsevier B.V. All rights reserved.