The copolymer (SASF) was synthesized by condensation of salicylic acid and semicarbazide with formaldehyde in the presence of 2M HCL as a catalyst at 126 ± 2 0C for 5 hrs. with molar proportion of reactants. Thermal study of the resins was carried out to determine their mode of decomposition and relative thermal stabilities by elemental analysis, FT-IR, UV-Visible 1H-NMR Spectroscopy. The thermal decomposition behavior of copolymer was studied by using TGA in static nitrogen atmosphere at a heating rate of 100C/min. Freeman Carroll and Sharp-Wentworth methods were used to calculate the thermal activation energy (Ea), the order of reaction (n), entropy Change (ΔS), free energy change (ΔF), apperent entropy change (ΔS), and frequency factor (Z). The thermal activation energy determined with the help of this method was in good agreement with each other. The antimicrobial activity for certain bacteria such as S. subtilis, E. coli, S. typhi, A. niger, S. aureus and C. albicans were studied.