X-ray diffraction patterns of FeAu and FePt have been measured at pressures up to ∼55 GPa with good signal-to-noise ratio and high resolution using synchrotron radiation. Rietveld analysis has been performed. The structure of FeAu is cubic in space group Fm3¯m with a lattice parameter a=3.9634±0.0012 Å.A third-order Birch–Murnaghan equation of state fit to the experimental data yields V 0=62.26±0.05 Å3, with a B 0 of 180.6±4.7 GPa and . The structure of FePt is tetragonal in space group P4/mmm with lattice parameters a=b=2.6748±0.0005 Å   and c=3.7375±0.0008 Å.A third-order Birch–Murnaghan equation of state fit to the experimental data yields V 0=26.74±0.01 Å3, with a B 0 of 264.1±9.8 GPa and .