Disclosed is a method for the continuous impregnation of wood elements, such as wood chips. The method comprises the subsequent steps of subjecting the wood elements to vacuum, to contact with acetylation fluid, and to impregnation pressure. Preferably, the process is conducted in a plant having conveyors, such as transportation screws, in suitable positions between the zones in which the subsequent process steps are conducted. The impregnation method is used in connection with the acetylation of the wood elements, and preferably is followed by a continuous acetylation process conducted in an acetylation reaction zone downstream of the zone where the impregnation is conducted.