A new method using microemulsified samples is presented. The method is suitable for the determination of manganese, present as methylcyclopentadienyl manganese tricarbonyl, in gasoline in the range 0∼75μg ml−1. The method has the advantage of simplicity, speed and the use of aqeous standards for calibration instead of organic standards. Coexistent elements do not disturb the determination. Results obtained by this method were better than those obtained by other methods for the same samples.