AbstractThe surface quality of thermally modified birch wood was examined after plane milling. The surface quality was assessed based on the arithmetic mean deviation of the assessed profile Ra. Plane milling was carried out at various cutting speeds of 20, 40, and 60 m/s and feed speeds 4, 8, and 11 m/min. Based on the results, it was concluded that thermal treatment reduced the surface roughness of milled birch wood, but the decrease was not statistically significant. The cutting speed and feed had the greatest impact on all monitored factors. Increases in cutting speed reduced the average roughness, while increases in feed speed had the opposite effect. The highest roughness was achieved after plane milling with a feed speed of 11 m/min.