In this thesis, we analysed the surface of beech (Fagus sylvatica L.) and spruce (Picea abies (L.) Karst.) wood after treatment with dielectric barrier discharge (DBD) plasma with a floating electrode. It is known that the effects of plasma treatment of wood surfaces are influenced by external (material and gas properties, electrode and reactor dimensions, electrical power, treatment time, etc.) and internal (plasma properties) factors. Plasma appearance was recorded with a camera and analysed using a computer program. By determining the contact angles of water on treated and untreated wood surfaces, the effect of changing the external parameters of the device on the wettability of wood was examined. The external parameters we varied were the speed of samples, the distance between the dielectrics (RME) and the distance between the wood surface and the dielectrics (RMES). Using the scanning electron microscope, the structure and topography of the sample surfaces were observed. The measured grey values of analysed discharge in the treatment of beech wood were higher than in the treatment of spruce wood. The results showed that the contact angle of the water droplets decreases as the speed of samples decreases. The surface of spruce wood is better wetted with water at RMES 0.5 mm and the surface of beech wood at 1 mm. The optimum RME for the spruce specimen is 8 mm, and for the beech, the best results are at 10 mm.