The first coordination sphere of Nd³⁺, Sm³⁺ and Yb³⁺ in glasses of the germanium chalcogenide-gallium chalcogenide system is studied by analyzing the optical transmission spectra of 0.85GeCh₂·0.15Ga₂Ch₃ glasses (where Ch = S, Se or Te) doped with chalcogenide of these metals. It is shown that the spectral shift in absorption bands of Nd³⁺ is a linear function of the mean electronegativity of chalcogens in the glasses, which indicates the coincidence between the average composition of the first coordination sphere of neodymium ions and the composition of anionic subsystem in the glasses under investigation. Spectral shift of absorption bands of Sm³⁺ and Yb³⁺ is a non-linear function of the mean electronegativity of chalcogens in the glasses.