Understanding how the pathway of formic acid electrooxidation depends on the composition and structure of Pt or Pd atoms on the surface of Pd- or Pt-based nanoparticles is important for designing catalysts aiming toward active, selective, stable, and low-cost. This work reports new findings of the investigation of submonolayer Pt decorated PdAu/C nanocatalysts (donated as Pt-PdAu/C) for formic acid electrooxidation. The Pt-PdAu/C are synthesized via a spontaneous displacement reaction and characterized by an array of analytical techniques including transmission electron microscopy, X-ray diffraction and Xray photoelectron spectroscopy. The electrocatalytic activity is examined using cyclic voltammetric and chronoamperometric measurements. The results show that the as-prepared Pt-PdAu/C with an optimal Pt:Pd atomic ratio of 1:100 exhibits enhanced electrocatalytic activity for formic acid electrooxidation compared with the PdAu/C and commercial the Pt/C catalysts. The oxidation potential on the Pt-PdAu/C shifts negatively by about 200 mV compared with that of the PdAu/C. The enhanced electrocatalytic activity and stability are attributed to the replacement of the Pd atom layer by Pt atoms, which significantly reduces the presence of the so-called "three neighboring site of Pd or Pt atoms in the Pt-PdAu/C to efficiently suppress CO formation. The enhanced activity/stability and ultralow Pt loading of the Pt-PdAu/C have implications to the development of commercially-viable catalysts for application in direct formic acid fuel cells and catalysis. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.