Abstract: The invention relates to a method for adjusting the quality factors of the surface of a piece of wood, so that the effective period of hydrogen peroxide, from its application onto the wood surface to its evaporation therefrom is less than 5 minutes, advantageously less than 1 minute. In the method onto the surface of the piece of wood, with a temperature near room temperature or lower, there is fed hydrogen peroxide as spray, the pH of the initial solution of said spray being neutral or acidic. The hydrogen peroxide is allowed to affect the wood surface about 1-60 seconds, advantageously about 1-30 seconds. Thereafter the hydrogen peroxide is activated by irradiating the surface of the piece of wood by a radiation source, so that at the end of the irradiation period, the wood surface temperature is 40-80° C. The power of the radiation source is 20-500 kW, advantageously 50-200 kW per surface m2 of the piece of wood.