This research paper aims at investigating the performance, emission and combustion characters of diesel engine with 20% volume concentrations of animal fat based biodiesel (AF020), waste cooking oil biodiesel (WCO20), camphor oil (CM020) and also including pure diesel fuel (D100). The peak cylinder pressure and heat release rate of biodiesel was about 4.82% higher and 13.49% lower than those of diesel fuel on average respectively. Start of combustion of alternate blends happened at earlier crank angles compared to base fuel. Combustion duration of all alternate fuel blends is higher than those of diesel at all load conditions. While fuelling CM020, AF020 and WCO20, the NOx concentration in the emission shows 7.52%, 10.352% and 16.405% increment respectively with the biodiesel addition to diesel. However, significant reduction in NOx of about 43.8% was observed for camphor oil-diesel blend when compared to other biodiesel blends. The correlation between NOx emission level and in-cylinder temperature was premeditated by a novel procedure using thermal imager. The result shows that the increase in in cylinder temperature contributed to the augmentation in NOx concentration. (C) 2016 Elsevier Ltd. All rights reserved.