Cardanol, a meta substituted phenol is a renewable organic resource obtained as a byproduct of the cashew industry. It is used for the production of polyurethanes. The cardanol-furfural resin has been synthesized by the condensation of cardanol with furfural in the presence of adipic acid catalyst and using varied molar proportion of the reacting monomers. The synthesized cardanolfurfural resin has been characterized by different physico-chemical techniques. The characterized furfuralated cardanol novolac resin has been condensed with toluene diisocyanate to produce hard segment polyurethanes. Soft segment polyurethanes are prepared by condensing the commercial polyol, polypropylene glycol-1200 (PPG-1200) with toluene diisocyanate and cardanol-furfural resin. Thermal stabilities of the polyurethanes were determined by Differential thermal analysis (DTA) and Thermo gravimetric analysis (TGA).Thermal decomposition curves were studied carefully with minute details. The Horowitz - Metzer and Broido methods have been used in the present investigation to calculate thermal activation energy. Thermal activation energy (Ea) calculated with above two mentioned methods are in close agreement.