The thermal dehydration and degradation of chitosan and heptylidene chitosan were studied by differential scanning calorimetry at four different heating rates: 5, 10, 15 and 20 K min(-1). The activation energy values of thermal dehydration and degradation of chitosan and heptylidene chitosan were investigated using different isoconversional and maximum rate (peak) methods viz. Kissinger-Akahira-Sunose (KAS), Tang, Starink, Flynn-Wall-Ozawa (FWO) and Bosewell. The variations of activation energy, E (alpha), with conversion function, alpha, established using these different methods were found to be similar. Compared to the FWO method, the KAS method offers a significant improvement in the accuracy of the E (a) values. All the maximum rate (peak) methods yielded consistent values of E (alpha) for the dehydration and degradation reactions of both chitosan and HEPT-chitosan. From the results, it can be concluded that one can follow the maximum rate (peak) methods to get the value of E (alpha) ; however, the complexity of the reaction can be identified only through isoconversional methods.