In this paper, the effect of the thermal barrier coated (TBC) on top of the piston used in CI engine was investigated when diesel and jatropha biodiesel (JB 100) were used as fuel. Two pistons were selected for TBC coating with a thickness of 50 μ as a bond coat and 250 μ as a topcoat. The first piston was coated with 7% YSZ (LHR 1) and second piston is coated with 2% Nd + YSZ (LHR 2) as a topcoat for the two pistons Ni–Cr–Al–Y used as a bond coat. Experiments were conducted to study the performance, emission and energy balance using standard piston and TBC-coated pistons. The results show that the BTE of an LHR 2 engine using JB 100 is 4.2% higher than the STD diesel engine. The BSFC of an LHR 2 engine using JB 100 fuel was reduced by 11.4% lower than the STD diesel engine. The HC and CO emissions were declined by 20% and 16% for the LHR 2 engine while comparing with the STD diesel engine and NOx emissions were increased by 15% in the LHR 2 engine with JB 100. © 2020, The Institution of Engineers (India).