[en] In this work, the structural and magnetic properties of polycrystalline Fe_xPt_1-x alloy thin films, with Fe composition x∼50 at%, deposited on different substrate and at distinct temperature, were investigated by X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). The films were prepared by DC magnetron sputtering technique on oxidized silicon (SiO₂/Si(1 0 0)) and MgO(1 0 0) substrates, with and without a Pt buffer layer, at substrate temperature (T_S) varying from room temperature to 600 deg. C. For the samples grown on amorphous SiO₂/Si, with and without a Pt buffer layer, the increase of T_S raised the crystallinity, but, did not induce a dominant face centered tetragonal, FCT(0 0 1) phase. In the FePt films grown on MgO, the XRD data showed the predominant ordered FCT(0 0 1) phase, with long-range order parameter of 0.89 at 600 deg. C. Also, during chemical ordering, the preferred crystal orientation changed from [1 0 0] FCT phase to [0 0 1] ordered FCT phase, through the intermediary [1 1 1] FCT phase. For FePt films on Pt/MgO, the Pt buffer's definite FCC(1 0 0) crystallographic structure was obtained at T_S=400 deg. C, allowing the adequate condition to induce the FCT structure with preferred (0 0 1) texture in the FePt film deposited on it, at this same T_S