Polycrystalline alloy thin films of Fe100-xPtx with various platinum compositions (x = 15, 24, 46 and 78 at.%) were synthesized by magnetron sputtering. The variation of platinum content and deposition rate with the platinum area target fraction in the sputtering was studied. It is observed that the X-ray diffraction patterns of as-deposited FePt films with all compositions exhibited a disordered phase with fee structure. The effects of annealing on the crystal structure and morphology are studied. Annealing of Fe54Pt46 films at high temperatures yielded an ordered L1(0) gamma(2) phase with face centered tetragonal (fct) structure. Differential scanning calorimetric (DSC) studies reveal exothermic peaks for phase transformation in different alloy compositions. The activation energies of phase transformations are estimated and the results are discussed. (C) 2003 Elsevier Science B.V. All rights reserved.