Heat capacities of two solid complexes of rare-earth elements with valine RE(Val)Cl-3 center dot 6H(2)O (RE = Nd, Er, Val = Valine) have been measured with a high-precision automatic adiabatic calorimeter over the temperature range from (78 to 376) K. An anomaly of a large step in the heat capacity curve was detected in the temperature range of roughly (308 to 314) K and (297 to 300) K for the Nd and Er complex, respectively, which may be attributed to a glass transition corresponding to freezing of structural disorder. Thermal decomposition of the two complexes was studied by a thermogravimetric (TG) technique, and the possible mechanism for the decomposition was suggested.