The thesis was based on lasting problem with processing beech wood. Beech wood (Fagus sylvatica L.), is the most prevalent wood species in Slovakia and it is the most important wood material utilized for industrial processing. Beech is wood with high frequency of defects such as red heartwood, reaction wood (tension wood), dote and so forth. Currently, due to the development of wood technology, it is necessary to respect the major limiting factors in manufacturing such as energy sources and sources of wood raw material. Considering the high proportion of beech wood, the way of its use is nowadays the subject of quality. The quality of beech wood is determined based on structure and properties of wood, frequency of defects in this material. Tension wood is thought of as an important wood defect because it causes negative alterations in solid wood quality and limits industrial utilization of wood. Findings confirmed 14 – 21 % ratio of tension wood in beech logs. Timber with content of tension wood has high longitudinal warping which affect their quality significantly. These timbers we need remove from another technological process or use many factors to arrange better quality. Thesis were described tension wood with scrutinized properties like a drying kinetics, and detailed observations about deformation in longitudinal and transverse plane, color changes and many other findings which are important for better understanding of tension wood in drying process and for industry utilization. Identification of tension wood is very important. The difference in drying of reaction and opposite samples was confirmed at all used temperatures. Ultimately, we can conclude that the differences in reaction and opposite samples drying are insignificant. If differences occur above the wood fibre saturation point, differences will come to minimum under the wood fibre saturation point, and conversely. The differences in density occur in measurement of samples in absolute dry state. Reaction samples had higher density as opposite samples. Longitudinal warping was significant in reaction samples. For measurement under industry conditions, we can say that further load of stack do not affect higher initial longitudinal warping and rather, it leads to contrary effect. We can prevent by the current problem of processing with correct understanding the behaviour of tension wood and identification through reagent and other properties.