The long range order as well as the short range order of magnetic Fe0.5Pd0.5 epitaxial thin films was studied. These alloys were elaborated by five methods: codeposition at room temperature, codeposition at room temperature followed by a 700 K annealing, codeposition at 600 K, and alternating deposit of pure Fe and pure Pd atomic layers at room temperature controlled either by the deposition time or by the reflection high energy electron diffraction oscillations. These samples were studied by x-ray diffraction (XRD) and polarized fluorescence extended x-ray absorption fine structure (EXAFS). These (001) oriented thin films have a face-centered tetragonal structure flattened along the growth direction. For each sample, a simulation program based on an inverse Monte Carlo method was used to build an atomic configuration satisfying both the long range order obtained by the XRD study and the directional short range order obtained by the EXAFS study. The best ordered sample (both on a long range and a short range scale) is the one codeposited at 600 K. © 1998 American Institute of Physics.