Ternary　Pt-Te-Ru　catalysts　with　different　atomic　ratios　were　synthesized　by　reducing　the　precursor　with　formic　acid.　The　physical　and　electrochemical　characterization　of　the　Pt3TeRu0.25/C　catalyst　was　performed　by　transmission　electron　microscopy　(TEM),　X-ray　diffraction,　energy-dispersive　X-ray　spectroscopy　equipped　with　TEM　(TEM-EDX),　X-ray　photoelectron　spectrometer,　ethanol　oxidation,　and　CO　stripping.　In　TEM　images,　the　Pt3TeRu0.25/C　nanoparticles　with　an　average　particle　size　of　around　2.9　nm　were　well　dispersed　on　the　carbon　support.　The　Pt　3TeRu0.25/C　catalyst　was　superior　to　the　Pt　3Te/C　catalyst　in　respect　of　catalytic　activity,　durability,　and　CO　tolerance.　The　positive　effect　of　the　Ru　presence　in　the　Pt3TeRu　0.25/C　catalyst　was　ascribed　to　the　interactions　of　Ru　or　Ru　oxides.　©　2008　Springer-Verlag.