Monodispersed FePt nanoparticles are synthesized by reduction of iron(II) acetylacetonate and platinum(II) acetylacetonate with 1,2-hexadecanediol as the reducing reagent in the polyol process. As-prepared FePt nanoparticles are chemically disordered with fcc phase. Transmission electron microscopy (TEM) images show a self-assembled particle array with an average particle size of 3 nm and a standard deviation about 10%. The transformation from chemically disordered fcc to chemically ordered Ll(0) phase is achieved by annealing at 650 degreesC for 30 min in Ar atmosphere where the oxygen level is less than 1 ppm. Magnetic hysteresis measurements show a coercivity of 9.0 kOe at 293 K, and 16.7 kOe at 5 K for the annealed FePt nanoparticles.