The thermal decomposition of Nafion has been studied by means of high-resolution and constant heating rate thermogravimetry
(TG), under nitrogen and synthetic air atmospheres. Nafion membranes have been studied in acid and salt (alkali chlorides)
forms. The TG curves of Nafion with alkali countercations show similar profiles, whichever the atmosphere employed. The kinetics
of thermal decomposition of the Nafion-Cs+ has also been studied. The method employed to calculate the kinetic parameters and to estimate the polymer lifetime from
the data was based on Kissinger's method.