The goal of this paper is to study thermal stability of some ferrocenes with acidic functional groups. Some other kinetic characteristics such as critical temperature and the rate constant corresponding to maximal degradation speed have been also evaluated. The type of functional units adjacent to the ferrocenyl unit determines thermal stability of ferrocene compounds. Groups with a powerful withdrawing effect determine a decreasing of the temperatures at which the material starts to lose weight. If a very long alkyl chain is connected to the ferrocene unit, a shielding effect in respect to the other carboxylic groups was observed, with an increase of the thermal stability.