Abstract The depletion of natural resources coupled with the alarming increase of pollution level is the driving force to use diesel in an environmentally benevolent manner. Research done till now is mainly focused upon the utilization of lower alcohols and information on higher alcohol blend is limited. The present study aims to investigate the effect of using a ternary blend of diesel, biodiesel, and decanol on a diesel engine. Tests were performed using decanol blended with biodiesel and diesel. The concentration of ternary blends were 10%, 15%, 20%, 30%, and 40% of decanol by volume while the diesel concentration was maintained to be 50% throughout. The study revealed that among the ternary blend, brake thermal efficiency increases with increase in the concentration of decanol. The brake specific fuel, and energy consumption decrease with an increase in alcohol content. Thus 40% decanol blend shows the least brake specific fuel consumption. NOx emission increased with the increase of alcohol concentration, whereas the emission levels of CO, HC, and smoke opacity decreased. Peak pressure is also found to be highest for 40% decanol blend and least for 10% decanol blend. With the addition of decanol content in the ternary blend, heat release rate is found to be increased whereas the cumulative heat release rate is observed to be reduced during the end phase of combustion. The study concluded that 40% blend of decanol, biodiesel and diesel can optimize engine performance and emission without performing any modifications in the CI engine.