The thermal stability of materials is an important issue to be assessed for different reasons. Many of them are stored in different temperature conditions or may undergo fire accidents. Thermal analysis techniques, with particular reference to thermogravimetry (TG) is a useful tool since it is able to determine the lower temperature limit for thermal decomposition upon heating a liquid or solid sample under a different temperature program set up.

Many authors often assessed the thermal stability of their materials on the basis of the onset decomposition (from a TG experiment under usual constant heating rate), but the value is affected by many variables and only a general relative scale may be constructed (if all the materials considered have similar structures and undergo the same reaction mechanism).

If this criterion is fulfilled in this lecture alternative stability parameters were taken into account, being derived by the kinetic analysis of the thermal decomposition (for some different materials). The limit of their use will be critically discussed.