This study analyzes the performance of biodiesel blended with diesel for fuelling a diesel engine. Biodiesel was produced from crude Jatropha oil with a high acid value (15.99 mgKOH/g) by using a two-step alkaline (base) catalyst process. The engine performance and emissions characteristics of Jatropha biodiesel blends of B5, B10 and B20 were studied and compared to those with conventional diesel at an engine speed range between 1100 to 2500 rpm. The results show that engine power output is less for all biodiesel blends tested when compared to 100% diesel, while the brake specific fuel consumption increases as the percentage of biodiesel increases. The torque obtained from the diesel engine for all Jatropha-biodiesel blends tested is lower than with 100% diesel at all engine speeds except for B5 that show higher engine torque in the speed range of 1100 to 2100 rpm. For the Jatropha biodiesel blends tested, there is lower emission of CO2 and unburned hydrocarbons, but there is increase in NOx emissions, compared to conventional diesel across the entire range of engine speeds examined.