The soil contaminated with petroleum products must be excluded from the crops and treated to reclamation processes. Natural processes of decomposition of hydrocarbon compounds go very slow, so it is necessary to use bioaugumentation or stimulation in order to accelerate the return of the soil to high culture. In this study the effect of hydrogen peroxide on the process of cleaning soil strongly contaminated with pertochemicals was investigated. For this purpose, a pot experiment lasting 60 days was carried. The dynamics of changes in the population of filamentous fungi, yeasts and bacteria were examined and also content of aliphatic hydrocarbons (n-alkanes), monoaromatic and polycyclic aromatic hydrocarbons (PAHs). Experimental use of hydrogen peroxide in the process of biodegradation of petroleum compounds assisted in the analyzed soil led to an increase of the number of grampositive bacteria during the test. Stimulation of oil products biodegradation by hydrogen peroxide also increased by 35% decomposition efficiency of aliphatic hydrocarbons (C8-C40) and about 50% PAH’s in comparison to control samples without hydrogen peroxide. There was no influence of hydrogen peroxide on the content of monoaromatic hydrocarbons (BTEX) with respect to controls, although in the end of experiment, the total concentration decreased by about 50% compared to the initial content.