A novel technique presented performs in situ remediation of soils contaminated by volatile organic compounds (VOCs) based on the use of electromagnetic fields for heating operations. Attention is focused on heat and mass transfer occurring in porous-moisturized media like a soil matrix. The microwave induced steam distillation process is investigated. Measurements are reported of temperature, humidity, residual contaminant concentration, and permittivity during the process. The crucial role is elucidated that the changes of the dielectrical properties of the soil matrix play on the electromagnetic field propagation. A mathematical model of the remediation process relating all the parameters above is proposed and validated.