Supercritical fluid extraction (SFE) using CO2 was performed on soil material artificially contaminated with diesel fuel. Raising the temperature from 313 K to 343 K caused the recovery efficiency to increase from 52 to 76%. Pressure and CO2 flow rate were found to be less important. As expected, increasing extraction time resulted in higher recoveries. Ultrasonic pretreatment of the soil material was found to be very effective, possibly due to disrupting the strong interaction bonding between soil matrix and contamination.