Used motor oil is known as one of the most massive dangerous wastes worldwide. This product composed of aliphatic hydrocarbon, aromatic or polycyclic aromatic hydrocarbons (PAHs), lubrication additives, heavy metals and various organic and inorganic compounds such as phosphorus, some chlorine and nitrogen compounds. Improper disposal at the land fields, non-principled drainage, road oiling, leaks from surface and subsurface storage tanks and leaks during motor operation will result in soil pollution to this compound. Generally speaking, various methods exist to modify and control the pollution of contaminated soils such as air stripping, soil washing, solidification and stabilization, vapor extraction, biological treatment and thermal treatment. Amongst, thermal procedure is one of the most appropriate techniques to clean the organic compounds off soil. Microwave with frequency of 0.3 to 300 GHz and wave length 1mm to 1 m can produce the required energy for increasing the soil’s temperature. In this case heat is generated within the material which leads to increasing efficiency of heating and maintaining the properties of the material surface. Also rapid and selective heating are other advantage of using microwave. In this study the process of eliminating used motor oil from soil with the use of microwave’s thermal energy is evaluated. During the conducted experiments, we concluded that the oil-contaminated soil has little ability to absorb the microwaves; as a result the temperature in bulk soil will not reach the required threshold for oil removal. Therefore compounds like magnesium dioxide and activated carbon were added to the soil for better absorption of waves and their performance in optimizing the removal efficiency was studied. Also, the effect of other factors like power (with the range of 400, 800 and 1000 Watt in activated carbon experiments, 800 and 1000 Watt in manganese dioxide experiments), time length (in 5 sets of 2, 4, 6, 8 and 10 minutes for both experiments), % moisture (in the range of 5, 10 and 15 percent of the dry soil’s weight) and absorbent dose (in 4 left; TEXT-INDENT: 28.35pt; MARGIN: 0in 0in 10pt; unicode-bidi: embed; DIRECTION: ltr" dir=ltr Keywords: Used motor oil, Soil, Microwave, Granular activated carbon, Manganese dioxide