Waste cottonseed oil was selected for biodiesel production. The transesterification results showed that with the variation of catalyst, methanol, variation of biodiesel production was realized. A maximum of 76% biodiesel was produced with 20% methanol in presence of 1.0% KOH. The engine experimental results showed that among three different blends of biodiesel (B10, B15 and B20), B10 blend of biodiesel has the highest performance characteristic value of brake power, brake thermal efficiency lowest value of brake specific fuel consumption and exhaust gas temperature. The experimental result also showed that the exhaust emissions including carbon monoxide (CO), hydrocarbons (HC) and smoke emissions were reduced for all biodiesel mixtures and hydrocarbon (HC) and NOx emissions of B10 blend is lowest among all the three blends of biodiesel there is a slight increase in the carbon monoxide (CO) emission for the B10 blend as compared to B15 and B10. However, a slight increase in oxidesof nitrogen (NOx) emission was experienced for biodiesel mixtures.