The terpolymers (2,4-DHPOF) have been synthesized by the condensation of 2,4-dihydroxypropiophenone with oxamide and formaldehyde in the presence of 2M HC1 as catalyst with varying proportions of reactants. Terpolymer composition has been determined on the basis of their elemental analysis. The terpolymer has been characterized by UV-visible, IR, and H-1 NMR spectra. The thermal decomposition behavior of some new terpolymers was studied using thermogravimetric analysis in air atmosphere at heating rate of 10 degrees C/min. Thermal decomposition curves are discussed with careful attention to minute details. The Freeman-Carroll and Sharp-Wentworth methods have been used to calculate activation energy and thermal stability. Thermal activation energy (E-a) calculated with the help of these methods are in agreement with each other. Thermodynamic parameters such as free energy change (Delta F), entropy change (A Delta S), apparent entropy change (S*), and frequency factor (z) are also determined on the basis of the TG curves and by using data of the Freeman-Carroll method. The Freidman method evaluated the variation in the apparent activation energy changes by isoconversional (model-free) kinetic methods. (C) 2009 Wiley Ileriodicals, Inc. J Appl Polym Sci 116: 619-627, 2010