Emission reduction of diesel engine is a keen interest for government and non-government automotive sectors. Identifying alternate fuels/additives to achieve this task is of continuing interest for researchers around the globe. Biodiesel derived from vegetable/non-edible oils are found to be more suitable for reducing diesel engine emissions. However, biodiesel fueled engines emit more Oxides of Nitrogen (NOx) during combustion. The engine performance, combustion and emission characteristics have been investigated for four different compositions of diesel-biodieselbutanol blends. Engine emissions for blends are very much reduced (NOx by 3.37 to 8.55%; smoke by 37.69% to 50.77%; CO by 55.55 to 70.37%) compared to diesel fuel. Addition of butanol has favored reduction in NOx emission but increases hydrocarbon emission in blends containing lower amount of biodiesel (<65%). The blend 50%D-5%B-45%BD produced high cylinder pressure and maximum heat release rate due to its enhanced premixed combustion. Combustion duration of diesel fuel is found to be low while combustion duration for blends increases with addition of biodiesel.