The novel terpolymer (1-N-4-SAHDF-Resin-II) has been synthesized by polycondensation of 1-Naphthol-4- sulphonic acid and Hexamethylene diamine with Formaldehyde in an acidic medium with molar proportion of reactants (2:1:3). To reveal the structure of the resin, the resin was characterized by elemental analysis and a spectral method, i.e. composition of terpolymer has been determined on the basis of its elemental analysis. The terpolymer resin has been characterized by FT-IR, NMR (1H & 13C) spectra and by SEM. For thermal decomposition studies, 1-N-4-SAHDF-Resin-II terpolymer has been studied by Thermo Gravimetric Analysis (TGA) at heating rate 10°C min-1 under nitrogen atmosphere. Detailed thermal degradation studies of the 1-N-4-SAHDFResin- II terpolymer has been carried out to ascertain its thermal stability. Thermal degradation plot has been discussed in order to determine their mode of decomposition, order of reaction(n), thermal activation energy(Ea), frequency factor(Z), free energy change(ΔF), entropy change(ΔS). Freeman – Carroll and Sharp- Wentworth methods have been applied for the calculation of kinetic parameters while the data from the Freeman – Carroll method has been used to determine various thermodynamic parameters. Thermal activation energy (Ea) values determined by these two methods were in good agreement with each other.