A polymeric resin was synthesized by the polycondesation technique of 4-hydroxybenzophenone and melamine with formaldehyde in the presence of 2M HCl as a catalyst. A polymer has been characterized by UV-Visible absorption spectra, Infra-red (IR) spectra and proton nuclear magnetic resonance (1H NMR) spectra. The morphology of polymer was studied by scanning electron microscopy (SEM). The thermal decomposition behavior of polymer (4- HBMF) was studied using thermogravimetric analysis in air atmosphere. 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 (Ea) calculated with the help of these methods are in agreement with each other. Thermodynamic parameters such as free energy change (∆F), entropy change (∆S), Apparent entropy change(S*) and frequency factor Z are also determined on the basis of TG curves and by using data of the Freeman-Carroll method. The order of reaction was found to be 0.98.