The thermal decomposition reactions of crystalline chelates of general formula Ln(thd)3 (Ln=La,Pr, Nd, Sm and Gd; thd=2,2,6,6-tetramethyl-3,5-heptanedione) have been studied by isothermal thermogravimetry. Several models were proposed initially
to calculate the kinetic parameters by isothermal method, thus the time reduced method was used to define the best kinetic
models. The Avrami–Erofeev (Am=2, 3 and 4) and R1 and R2 models presented good agreement with experimental data, as well as, linear correlation coefficient
(r) and standard deviation (s).