FePt and Ag-doped FePt nanoparticles were synthesized by the thermolysis and polyol reductions. The Al-to-L1(0) transformation of the nanoparticles was investigated by differential scanning calorimetry (DSC) at different scanning rates, and the DSC endothermic peak shifts were monitored and used for the Kissinger analyses. The activation energy for the phase transformation was determined to be similar to 251 and similar to 219 kJ/mol for the pure and doped FePt nanoparticles, respectively. The decrease in the activation energy is the evidence of increased number of vacancies, which turned out to be the origin for the reduced L1(0) chemical ordering temperature in doped FePt. (c) 2007 Elsevier B.V. All rights reserved.