[en] The isothermal section of the phase diagram of the Gd-Fe-Sb ternary system at 773 K has been investigated mainly by X-ray powder diffraction. This isothermal section consists of 12 single-phase regions, 21 two-phase regions and 10 three-phase regions. The homogeneity range of FeSb phase extended from about 44 to 46 at.% Sb. Binary compounds, FeSb, FeSb₂, Fe₁₇Gd₂, Fe₃Gd, Fe₂Gd, Gd₅Sb₃, Gd₄Sb₃, GdSb and Gd₁₆Sb₃₉ have been confirmed while no ternary compound has been observed. The maximum solid solubility of Gd in FeSb phase is about less than 1 at.% Gd, while the homogeneity ranges of other phases were not observed