A new single source approach was developed to synthesize face-centered tetragonal (fct) FePt nanoparticles using bimetallic compound (CO)3Fe(mu-dppm)(mu-CO)PtCl2, which has been characterized by single crystal X-ray diffraction and was used as the precursor to ensure the accurate stoichiometry of the final FePt product; the ability of the molecular complex to act as a single source precursor for the formation of fct FePt nanocrystals with an average diameter of 3.2 nm has been demonstrated.