In the past few decades, use of energy resources in industrial and transportation sector have reached to its peak resulting in depleting resources and environment squalor. Vegetable oils, which have properties comparable to diesel fuel, are considered promising alternative fuels for unmodified diesel engines. However, high viscosity of vegetable oils is a major challenge which could be reduced by blending with alcohols. The aim of the present study was to investigate the suitability of orange peel oil and n-butanol blends as an alternative fuel for CI engine. Various blends of butanol with orange peel oil were prepared on volumetric basis and named as B10OPO90 (10% n-butanol and 90% orange peel oil), B20OPO80 (20% n-butanol and 80% orange peel oil), B30OPO70 (30% n-butanol and 70% orange peel oil) and B40OPO60 (40% n-butanol and 60% orange peel oil). All blends were found homogenous and various physico-chemical properties were evaluated in accordance to relevant standards. In the subsequent phase of experiments, exhaustive engine trials were carried out on a single cylinder medium capacity diesel engine using the different test fuel samples. Kinematic viscosity of blends was found to be decreasing for blends of n-butanol. But, with blends, brake thermal efficiency (BTE) was found to be lower than diesel fuel. CO emission indicates that by increasing the percentage of n-butanol in the blends, there is an appreciable reduction in emission at high loads over the baseline data of diesel. NOx emission was found to be lower for all the blends at full load condition, while smoke opacity was higher for all loads.