CaO was oxidized with H(2)O(2) in presence of stabilizers (MgSO(4), water glass, K(4)P(2)O(7) com. phosphonates) and modifiers (KH(2)PO(4), K(2)HPO(4), urea) to CaO(2) used then for enhancement of biodegrdn. of petroleum-derived polycyclic arom. hydrocarbons (PAH) in soil and bottom deposits. The addn. of CaO(2) (5 g/kg and 0.05 g/kg, resp.) resulted in an increase of the PAH removal degree by 15-20%.