Oxygen containing additives are usually used to improve gasoline's performance and reduce exhaust emissions. In this study, the effect of oxygen containing additives on gasoline blended fuels on exhaust emissions was investigated for different engine speeds in a single cylinder, four-stroke, spark-ignition engine. The results indicate that CO and HC exhaust emissions are lower with the use of ethanol-gasoline and DMC-gasoline blended fuels as compared to the use of unleaded gasoline. On the other hand, the effect of ethanol-gasoline and DMC-gasoline blended fuels on NO(x) exhaust emission is insignificant. Using oxygen containing additives can increase fuel consumption as a result of the heating value of the blended fuels being lower than that of unleaded gasoline. (C) 2009 Elsevier Ltd. All rights reserved.