Achieving higher efficiency in IC engines is where a lot of research went into for the past one century and even with the effort of all the research the nominal efficiency is 31 percentages.The remaining energy is rejected in the form of heat and friction in the engine.The diesel engine usually offers better efficiency than petrol engine. Even the diesel engine loses about two thirds of the heat energy produced from the fuel, one-third to the coolant, and one third to the exhaust, leaving only about one-third as useful power output. Theoretically we can improve the thermal efficiency of the engine by decreasing the energy loss unless the second law of thermodynamics is not violated.In order to improve the thermal efficiency of the Internal Combustion Engines the heat energy rejected to the coolant is reduced by coating the pistons with a Thermal Barrier Coating (TBC). The main function of the TBC is to reduce the heat energy transferred through the piston body. The types and effects of different types of TBC are discussed here.