In continuation of the previous work, practical proton ligand and metal ligand stability constants of the metal ions Y(III), Nd(III) and Pr(III) with glutamic acid ligand at temperature 203 K at constant ionic strength of 0.1 M KNO₃ was determined. The stability constant was determined by the method of Bjerrum Calvin pH titration technique as adopted by Irving and Rossotti^1-2. The stability constant of metal complexes with glutamic acid shows the sequence Y (III) > Nd(III) > Pr (III). Thermodynamic parameters such as free energy (DG), enthalpy charge (DH) and entropy charge DS also have been calculated.