This work examines the feasibility of fuelling methyl ester derived from green algae, Chlorella emersonii in a compression ignition engine. This work also proposes Chlorella emersonii methyl ester (CEME) as a potential alternative energy source since the above species is available extensively in fresh water, marine and aquatic ecosystems throughout the world. CEME was blended with petroleum diesel fuel at various volume proportions of 10%, 20%, 30%, 40% and 100% and their properties were analyzed as per ASTM standards for its application as biofuel. The prepared test fuels were analyzed experimentally in a single cylinder diesel engine at constant speed (1500 rev/min) for its performance, combustion and emission (regulated and unregulated) characteristics. Test results projected that, the characteristics of 20% CEME+80%diesel fuel blend was in par with diesel fuel in terms of thermal efficiency, THC, CO and smoke emissions. However, CEME blends resulted in slightly higher levels of CO2 and NOx emissions. In terms of unregulated emissions, CEME blends in diesel showed lowered toluene and acetaldehyde emissions. However, acetone and formaldehyde emissions increased with higher percentage of CEME in diesel blend. At full load, the attained cylinder pressure and heat release rate of CEME were comparatively lower than diesel fuel. (C) 2019 Elsevier Ltd. All rights reserved.