In this study, we have discussed the thermal behaviour of intumescent coating. Intumescent coating is an insulating system designed to decrease heat transfer from a fire to substrate structure to maintain its integrity. The coating was based on Expandable Graphite (EG), Ammonium Poly Phosphate (APP), melamine, boric acid, kaolin clay (Al2Si2O5(OH)4), bisphenol. A epoxy resin BE-188 (BPA) and ACR hardener H-2310 polyamide amine as curing agent. Different formulations were developed to study the heat shielding effect. The C4 formulation showed better result on the heat shielding effect; it is further modified by adding kaolin clay 3-5 wt in the next three formulations. Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM) was done to study thermal analysis and char morphology of the formulations. The result showed that by adding the filler kaolin clay, the fire retardant time of coating was extended. The result showed that thermal behaviour of intumescent coating formulation was improved with 5 wt of kaolin clay. © 2011 Asian Network for Scientific Information.