The efficiency of any internal combustion engine depends upon the heat energy available for combustion. In this paper, a theoretical analysis was carried out on both uncoated and coated piston to find the temperature distribution over the piston length. Even though many coating materials are available and they have their own advantage and disadvantage, in this work, Alumina has been taken based on the literature. Also the analysis was carried out with various coating thicknesses such as 60, 70,80, 90 and 100 microns. It is found that a drastic difference was found in between uncoated and coated piston. The coated piston showed very high thermal barrier capability than uncoated piston. Also the coating thickness does not produce much impact on thermal capability. But since the higher level of thermal coating will lead to increase of chamber temperature, it may lead to knocking of an engine. Hence, an optimum thickness of 100 microns was considered suitable for SI engine applications.