The process of purification of petroleum wastewater by electron beam irradiation using a theoretical model that describes the reactive species generated during the irradiation process and the reactions with the contaminating substances was analyzed. For the irradiation process, a linear electron accelerator with absorbed doses of 18 and 23 kGy was used on 10 L samples of oil wastewater. The parameters analyzed were: COD, BOD, pH, dissolved oxygen, electrical conductivity, barium ion, sulfates and calcium ion. The main results show that the purification through the use of electron beam allows the elimination of contaminants such as: COD, BOD, electrical conductivity, barium ion and calcium ion in a percentage range between 16 and 80%. The higher the absorbed dose, the greater the purification percentages of these contaminants. Sulfates, as well as suspended solids in the sample, have contradictory behaviors. After irradiation at the higher absorbed dose (23 kGy), there is an increase in the initially measured values. This could be due to a large evaporation of water from the residual water sample.