Biodiesel is a renewable fuel and can be used in neat form or blend with diesel fuel for reducing the dependency on fossil fuel and environmental degradation.The main aim of this study was to evaluate the combustion parameters of a direct injection (DI) diesel engine run on B20-a biodiesel, and diesel blend comprising 80% diesel and 20% Jatropha methyl ester (JME) in it and compare the results with the baseline results of the same engine run on diesel. The experiments were performed on a single-cylinder, air-cooled, four-stroke, DI constant speed of 1500 rpm, and rated power of 4.4 kW diesel engine which was run at an optimum condition for JME20. Further, an investigation was carried out to assess the engine behavior in terms of the combustion parameters of the engine run on Diesel and JME20 when the piston was coated with two different thermal barrier-coating materials namely Yittria-Stabilized Zircoina (YSZ) and YSZ+Cerium Oxide (CeO 2 ). Combustion parameters such as cylinder pressure, heat release rate, and ignition time, etc. on different fuels tested were determined, compared with baseline results, and presented in this paper.