Differential thermal analysis and differential scanning calorimetry were used to investigate phase equilibria in the AgCl-LnCl 3 (Ln = Ce, Sm, Gd) binary systems. It was found that systems under investigation represent typical examples of simple eutectic systems. The eutectic compositions and eutectic temperatures were found to be: x(CeCl 3) = 0.095, T eut-= 700 K (for AgCl-CeCl 3), x(SmCl 3) = 0.228, T eut = 644 K (for AgCl-SmCl 3) and x(GdCl 3) = 0.288, T eut = 609 K (for AgCl-GdCl 3). The thermodynamic functions of mixing in AgCl-LnCl 3 systems (Ln = Ce, Nd, Sm, Gd) were predicted on the basis of experimental data using the CALPHAD method by association model (AM) and Redlich-Kister model (RKM). The possibility of existence of the associates in the liquid phase was discussed.