Electrocatalytic formic acid oxidation is examined on electrodeposited Pt100-xPbx thin films grown on textured Au(111). Metastable fcc Pt100-xPbx (0 < x atom % < 50) films exhibit significantly enhanced catalysis for formic acid oxidation relative to Pt films of similar roughness. At - 0.15 V SCE an enhancement factor in excess of 100 is evident between Pt83Pb17 and Pt films of similar roughness. Electrodeposition of near stoichiometric PtPb thin films yields a smooth compact surface that exhibits enhanced electrocatalytic activity relative to a Pt electrode. X-ray diffraction reveals a P6(3)/mmc intermetallic phase while TEM indicates the formation of fcc Pt100-xPbx lattice with dimensions almost lattice matched to Au(111) and/or Pt3Pb. After considering the surface roughness, the electrocatalytic activity of the compact PtPb and rough metastable fcc phase are similar in magnitude. Durability was examined by chronoamperometry and cyclic voltammetry. The Pb-rich and PtPb films are substantially dealloyed particularly at higher potentials. The dealloyed structure still exhibits significant electrocatalytic behavior that is presumably related to Pb upd on available Pt surface sites. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3599913] All rights reserved.