The phase equilibria in the Gd–Ni–Sn ternary system were determined at 770K by means of X-ray and metallographic analyses in the whole concentration range. The Gd–Ni–Sn system is characterized by formation of 14 ternary intermetallic compounds: GdNi 4.89 Sn (CeCu 4.38 In 1.62 -type), Gd 12 Ni 6 Sn (Sm 12 Ni 6 In-type), Gd 6 Ni 2 Sn (Ho 6 Co 2 Ga-type), Gd 2 Ni 2 Sn (W 2 CoB 2 -type), GdNiSn (TiNiSi-type), Gd 2 Ni 7 Sn 3 (Dy 2 Ni 7 Sn 3 -type), Gd 3 Ni 8 Sn 4 (Lu 3 Co 7.77 Sn 4 -type), GdNi 3 Sn 2 (HoNi 2.6 Ga 2.4 -type), GdNi 2 Sn 2 (LaPt 2 Ge 2 -type), GdNiSn 2 (LuNiSn 2 -type), Gd 3 Ni 4 Sn 6 (Ce 3 Pd 4 Sn 6 -type), Gd 40 Ni 15 Sn 45 (structure unknown), GdNi 2.67 Sn 5.44 (GdNi 2.67 Sn 5.44 -type), and GdNiSn 4 (LuNiSn 4 -type). The crystal chemistry analysis of ternary compounds formed in the Gd–Ni–Sn system was done.