[en] The isothermal section (500 deg. C) of the phase diagram of the Gd-Fe-Ga ternary system was investigated by X-ray powder diffraction analysis. Eleven binary compounds, GdGa₂, GdGa, Gd₃Ga₂, Gd₅Ga₃, GdFe₂, GdFe₃, Gd₂Fe₁₇, Fe₃Ga, Fe₆Ga₅, Fe₃Ga₄ and FeGa₃, have been confirmed. Two ternary compounds, GdFe_5.3Ga_6.7 and GdFe₅Ga₇, were found in this ternary system at 500 deg. C. The compound GdFe_5.3Ga_6.7 is orthorhombic ScFe₆Ga₆-type structure (space group Immm) with a = 0.8567 (9), b = 0.86960 (9) and c = 0.50782 (5) nm, while the compound GdFe₅Ga₇ is tetragonal ThMn₁₂-type structure (space group I4/mmm) with a = 0.8651(1) and c = 0.50934 (6) nm. The isothermal section at 500 deg. C consists of 16 single-phase regions, 31 two-phase regions and 16 three-phase regions. The maximum solid solubilities of Ga in GdFe₂, GdFe₃, Gd₂Fe₁₇ are 9.2, 9.0, and 44.3 at.% respectively. The homogeneity range of GdGa₂ is from 22 to 33.3 at.% Ga in Gd-Ga side but the solid solubility of Fe in this compound is very small. The homogeneity range of GdFe₅Ga₇ is from 53.8 to 59.2 at.% Ga. Very limited solid solutions were measured in the other compounds.