Diesel Engines are widely used in transportation, industrial and agriculture sectors worldwide due to their versatility and ruggedness. However, they also emit harmful emissions detrimental to human health and environment. Apart from environmental degradation, the perturbation in international crude oil prices is also mandating use of renewable fuels. In this context, vegetable oils such as Jatropha Curcas due to their carbon neutral nature and widespread availability, seems to present a promising alternative to the mineral diesel. Straight vegetable oils (SVO) are not recommended for direct diesel engine application due to their higher viscosity, poor volatility etc. and dilution of straight vegetable oil may effectively enable its direct application in unmodified diesel engines.In the present study, Jatropha oil was diluted with n-Butanol to improve the fuel properties of the blend. Butanol was considered due to its lower viscosity, oxygenated nature and complete miscibility with Jatropha oil. Three different blends were prepared having 5%, 10%, 20% n-butanol mixed with 95%, 90% and 80% Jatropha oil respectively. Various physico-chemical properties were evaluated for JO-n-butanol blends. Exhaustive engine trials were carried out on an unmodified diesel engine and the results were compared with baseline data of diesel. The results indicated that there was a marginal decrease in heating value, kinematic viscosity, density and specific gravity by increasing the percentage of n-butanol in Jatropha oil. Brake thermal efficiency was found to increase and brake specific energy consumption was reduced with JO-n-butanol blends. A considerable reduction in emissions of carbon monoxide, carbon dioxide, smoke and oxides of nitrogen was observed during the engine trial. However, emissions of unburnt hydrocarbons were found to be marginally higher for JO-n-butanol blend as compared to diesel baseline.