Abstract: Erbium rare earth complex with valine,Er(Val)Cl3·6H2O,was synthesized.Properties of the complex were determined by EDTA titration,elemental analysis,infrared spectral analysis and melting point measurement.Its hermal decomposition mechanism was deduced through thermogravimetry and differential thermal analysis.The results showed that the thermal decomposition procedure was mad up of a dehydration process,the break up of amino acid reactions as a fitted framework, and the final decomposed product being a rare earth basic salt.The non-thermal kinetic study on the first two step thermal decomposition reactions was performed with the methods of Achar and Coats-Redfern.The activation energies of the two reactions were determined to be 123.42?kJ·mol-1 and 222.83?kJ·mol-1,respectively,and the values of logarithm of preexponential factor were 36.31 and 41.00,respectively.Kinetic equations for the studied reactions were fitted.