The current study investigates the opportunity of using olive mill wastewater (OMWW) as a renewable fuel in internal combustion engines. The biofuel was made from the hydrothermal conversion of OMWW using sub-/supercritical alcohol-water system. OMWW biofuel was blended with pure diesel (designated B0). Three blends namely B10, B20 and B30 containing respectively 10%, 20% and 30% by volume of biofuel were tested. This paper focuses on the experimental study of the performance, combustion and emission characteristics of a diesel engine using OMWW biofuel as a partial replacement of conventional diesel fuel. All experiments were performed with constant engine speed (1500 rpm). The engine load was varied from 20 to 100% of full load. It is found that B10 blend offers the best results, compared to B20 and B30, in terms of performance and pollutant emissions. Using B10 showed a lower emission levels for unburned hydrocarbons (12%), particulate matter (12%) and carbon monoxide (26%) under high load conditions, compared to that of B20. Moreover, under medium load conditions, B10 further reduced the concentration of pollutants such as particulate matter (55%) and carbon monoxide (65%) compared to that of B30. In addition, the use of B20 and B30 blends resulted in a lower thermal efficiency than that of diesel fuel. Conversely, the thermal efficiency obtained with B10 was the highest even compared to diesel fuel.