Thermal characterization of maleic anhydride-styrene-allyl propionate (MA-St-AP) terpolymer and its ester derivatives named as n-alkyl maleate and shown as nPr MA-St-AP, nBu MA-St-AP, nPn MA-St-AP, and nBz MA-St-AP was carried out. The thermal characterization was performed using thermal analysis techniques such as TGA, DTA, DSC, and TMA. Different results were observed between the original terpolymer and its ester derivatives. Thermal stabilities of the terpolymer and its ester derivatives were compared by using various measurements plotted as TGA, DTA, DSC, and TMA curves. The increase in the alcohols' carbon numbers added to the original terpolymer results in ester derivatives with different thermal stability behavior. (c) 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 600-604,2007