Sand apple oil seed that has relatively high oil yield is widely cultivated in Africa. Evaluation of the performance of sand apple ethyl ester is a missing link in establishing it as an alternative fuel for use in diesel engines. Performance evaluation of optimized yields of sand apple biodiesel was, therefore, conducted in a diesel engine at various loading rates. Oil was extracted from sand apple seeds via solvent extraction. A Central Composite Design was used to optimize biodiesel yields from sand apple oil transesterification using potassium hydroxide as catalyst. Engine tests were carried out to evaluate the performance of a stationary 5Hp diesel engine starting from 0% to 100% load conditions. The engine was run with diesel and four different blends of diesel/biodiesel. Values for speed, torque, fuel consumption rate and exhaust temperature were determined. The optimum biodiesel yield recorded was 94.6%. The torque, speed, fuel consumption rate and exhaust temperature recorded for best engine performance for all blends were 8.50 Nm, 2950 rpm, 2.925 x 10(-6) kg/s, and 300 degrees C. The evaluated engine parameters showed sand apple biodiesel can be burned in diesel engines using appropriate blending ratio without any modification to the engine. (C) 2018 Elsevier Ltd. All rights reserved.