Abstract: In this study, engine performance and exhaust emission tests were performed using pure gasoline and volumetrically 10% ethanol-C2 or methanol-C1/gasoline blends (G100, E10, and M10) fuels in a single-cylinder, four-stroke, water-cooled, spark-ignition (SI) engine under constant engine speed (1500 rpm) and different loads (25%, 50%, 75%, and 100%). In the tested engine, the brake specific fuel consumption values of G100, M10 and E10 fuels under full load condition were found to be as 0.279 kg/kWh, 0.296 kg/kWh and 0.307 kg/kWh, respectively. When the exhaust emissions were examined, E10 and M10 fuels were observed to have lesser CO, CO2, NOX, and HC emissions compared to pure gasoline. The lowest CO emission was determined as 3.15% for E10 fuel at 75% load. NOX emission decreased with the increase of engine load in all fuel blends, the best performance is measured as 908.86 ppm in E10 fuel at 100% load. The minimum HC emission for E10 fuel was measured as 116.36 ppm at 75% load. Compared with G100 fuel, E10 and M10 blends emitted 39% and 35% less HC emissions, respectively at 75% load. In addition, E10 and M10 fuels generated 8% and 5% less CO2 emissions at all engine loads, respectively, as compared to G100 fuel. As a result of thermodynamic analyses; The highest exergy efficiency values were found to be at 21.0% for G100, 17.92% for E10, and 16.85% for M10, respectively. Besides, the energy efficiencies were obtained to be as 30.01% for G100, 28.33% for E10, and 29.90% for M10, respectively. According to the sustainability analysis, E10 fuel performed better results than M10 fuel in order to be an alternative to G100 fuel.