Use of biodiesel in a conventional diesel engine brings about a considerable reduction in carbon dioxide, carbon monoxides and particulates. This type of fuels would reduce the share of carbon in particulates. Biodiesel fuel was produced by converting non-edible rapeseed oil through the transesterification reaction. This study analyzed the effect of different levels (0, 10 and 20 vol%) of biodiesel fuel from non edible rapeseed on performance and exhaust emissions of a single-cylinder air-cooled diesel fuel, at different engine speeds (from 1800 to 3000 rpm) and under two loading states (75 and 100%). Study results showed that the B10D90 blend had the highest power and torque values at 2600 and 1800 rpm, respectively. The B10D90 blend also had the lowest specific fuel consumption at 1800 rpm. At 75% loading and 1800 rpm, B20D80 had the highest NOx and CO emissions, whereas B10D90 had the lowest NOx and CO emissions at 3000 rpm. Higher biodiesel to diesel ratios resulted into reduced power output and torque at the highest engine speed (3000 rpm). At high engine speeds, torque and specific fuel consumption under full loading decreased and increased, respectively. Under 75% loading, NOx emissions was also reduced for all fuel blends, whereas CO emissions decreased for all fuel blends except for the diesel fuel. Finally, the B10D90 blend under 100% loading and at 1800 rpm was selected as the best fuel in terms of the best performance. Moreover, the B10D90 blend under 75% loading and at 3000 rpm was selected as the optimum blend in terms of pollution in a single-cylinder diesel engine. (c) 2016 Elsevier Ltd. All rights reserved.