In this study, first, the effects of addition of 10% (Pen10), 20% (Pen20), and 30% (Pen30) pentanol on the performance, combustion, and emissions of a diesel engine were investigated. Then, the effect of injection timing for Pen30 fuel was investigated by changing the original injection timing of 20 to 22 and 24 degrees BTDC (before top dead center). The engine tests were performed under different loads at 2400 rpm. The results indicated that, with the advancing of the diesel injection timing and increasing the pentanol ratio in the fuel blends, the ignition delay increased and the start of combustion delayed. The maximum heat release rate and cylinder pressure values of pentanol blends were found to be higher than those of diesel fuel. Both the maximum cylinder pressure and the maximum heat release rate increased with the advancing of the diesel injection timing to 22 and 24 degrees BTDC. Brake-specific fuel consumption value of Pen30 was higher than that of diesel fuel at the original injection timing, and it decreased as the injection timing was advanced to 22 and 24 BTDC as compared to that of the original injection timing. NOx emission decreased with the increasing pentanol fraction. Also, NOx emissions increased significantly at 24 BTDC injection timing but decreased slightly at 22 degrees BTDC injection timing. Smoke emissions of the pentanol blends are lower than those of the diesel fuel under all operating conditions as well as decreased with the advancing injection timing.