The paper presents results of influence of thermal modification on cutting power required for milling wood processing. The experiment was conducted for the different treatment temperatures (170°C, 190°C and 210°C) and different technological parameters of processing (feed and cutting depth). Cutting powers during milling were measured on four groups of beech wood samples, dimensions 35×16×400 mm, separately for heartwood and sapwood. The following mechanical and physical properties of the processed samples were tested: bending properties (modulus of rupture and modulus of elasticity), cross-sectional and tangential hardness, and air-dry density. The measuring device used for measuring, monitoring and displaying cutting power was developed at the Wood Machining Centre at the Faculty of Forestry in Belgrade. The results point out the differences in the powers required for processing heat-treated wood compared to untreated wood. The analysis shows that with the increase in treatment temperature, the required cutting powers decrease.