Two solid-state coordination compounds of rare earth metals with glycin, [Gd4/3Y2/3(Gly)(6)(H2O)(4)](ClO4)(6)(.)5H(2)O and [ErY(Gly)(6)(H2O)(4)](ClO4)(6)(.)5H(2)O were synthesized. The low-temperature heat capacities of the two coordination compounds, were measured with an adiabatic calorimeter over the temperature range from 78 to 376 K. [Gd4/3Y2/3(Gly)(6)(H2O)(4)](ClO4)(6)(.)5H(2)O melted at 342.90 K, while [ErY(Gly)(6)(H2O)(4)](ClO4)(6)(.)5H(2)O melted at 328.79 K. The molar enthalpy and entropy of fusion for the two coordination compounds were determined to be 18.48 kJ mol(-1) and 53.9 J K-1 mol(-1) for [Gd4/3Y2/3(Gly)(6)(H2O)(4)](ClO4)(6)(.)5H(2)O, 1.82 kJ mol(-1) and 5.5 J K-1 mol(-1) for [ErY(Gly)(6)(H2O)(4)](ClO4)(6)(.)5H(2)O, respectively. Thermal decompositions of the two coordination compounds were studied through the thermogravimetry (TG). Possible mechanisms of the decompositions are discussed.