While bimetallic AuPt nanoparticles have been shown to exhibit synergistic catalytic activities in fuel cell reactions, the precise control of the bimetallic composition presents an important challenge. This presentation describes the findings of a new approach to the synthesis of monodispersed PtAu nanoparticles, which involved thermal control and chemical reduction of HAuCl4 and H2PtCl6 in organic solvents. The composition of PtAu nanoparticles can be controlled by varying feeding ratio of Pt and Au precursors and manipulating reaction time and reaction temperature. The as-synthesized AuPt nanoparticles were characterized by TEM, DCP, XRD and UV-Vis techniques, which allowed us to develop some insights into the mechanistic aspects for the size and composition control. The results from the study of the electrocatalytic activities of the PtAu nanoparticles supported on carbon materials are also discussed.