STUDY OF THE THERMAL OXIDATION BEHAVIOUR OF SOME PHOTOCROMIC MATERIALS In this paper the behavior at elevated temperatures (thermal oxidation) of some new copolymers exhibiting photochromic properties has been studied. These copolymers were prepared by chemical grafting of some azoic dyes on the support-polymers chains. The thermal oxidation has been studied by DTA, TG and DTG in the range of 22°C - 500°C for both support-copolymers and grafted photochromic polymers. The experimental data suggest that, upon heating, various oxidation processes occurs which are accompanied by slight increasing of the sample weight (at moderate temperatures), and oxidative decomposition processes accompanied by more or less intense decreasing in sample weight (at higher temperatures, over 300°C). The temperature values corresponding to these transformations seem to be related to both the polymer and grafted substituent structures. Thus, the halogen containing substituents induced a significant increasing in stability, especially in the case of chlorine containing ones. The imide structure of these substituents seems to induce a higher stability as compared to amic one.