This paper aims to investigate the performance of a four-stroke single cylinder variable compression ratio diesel engine using blend of lemongrass biodiesel (LGBD) as fuel. Initially, the biodiesel produced from lemongrass oil by transesterification process and can be used as an alternative fuel for diesel engine. “The experiment was carried out in a variable compression ratio diesel engine using LBD20 (20% lemongrass biodiesel + 80% Diesel by v/v basis) to study the performance parameters like brake thermal efficiency (BTE) and brake-specific fuel consumption (BSFC) and exhaust gas emissions like Carbon monoxide (CO), hydrocarbon (HC), oxides of nitrogen (NOx) and smoke opacity emissions were measured with different compression ratios like 16.5:1, 17.5:1, 19:1 and 20:1 at different loads and compared with diesel fuel”. “The results revealed that the maximum brake thermal efficiency obtained is about 31.02% for LGBD20 at CR20, which is higher than that of diesel (31.8%). The exhaust emissions CO and HC were reduced by 36% and 24% for LGBD20 mixture of biodiesel when compared to diesel. However, there was increase in NOx by 28% compared to the diesel fuel”. © 2020 Elsevier B.V., All rights reserved.