Studies of non-isothermal decomposition of certain iodo-organometallic arylidene polyesters and organometallic arylidene polyesters have been performed with TGA measurements at atmospheric pressure. The analysis of the non-isothermal TG and DTG curves of the samples under investigation revealed that their decomposition course proceeds via three stages. The kinetic parameters such as activation energy (E,), preexponential factor (A) and entropy of activation (AS*) for all polymers at different decomposition stages are determinedfrom an appropriate kinetic equation. More particularly, the data showed that the thermal stability of some of the polymers decreases with increasing ring size of arylidene moieties. Furthermore, the effect of absence of iodoand presence of-OCH₃ groups upon the thermal properties of polymers was also evaluated.