The emphasis to conserve petroleum-based fuels has provided the motivation for several studies on the development and testing of alternate fuels in diesel engine. This paper investigates the effect of using diesohol (ethanol-diesel blend) as a fuel in a DI diesel engine. In this investigation, two different composition of diesohol were selected for examination. One was 5% ethanol and 95% diesel and another one was 10% ethanol and 90% diesel. In order to avoid phase separation of diesohol, the blend was preheated to 35°C. The result of pure petroleum diesel fuel operation was taken as a base line reading to examine the effectiveness of the two diesohol compositions. The result shows that the use of diesohol, keep the combustion temperature low. It also resulted in reduction in NOX and smoke emission. This undoubtedly proved that diesohol can be used in diesel engine without any major modification in the engine. © 2015 Journal of Chemical and Pharmaceutical Sciences.