Wood is used arter drying until equilibrium moisture content (EMC) levels determined by the elimatic conditions of usage area. But in practice, the moisture content (MC) levels of the wood reaches higher values than expected for a usage area, as the wood usually remains under outdoor elimatic conditions for a longer period of time before use. Determination of the adsorption tendeney according to the elimatic conditions of waiting area before the usage is of great importance for the usage aim. In the study, adsorption properties of eastern beech were deterınined in three different MC conditions of wood using three different thicknesses. Fourier equation was used in the deterınination of wood ınoisture, and Fourier equation constants were defined in case of adsorption. The results of the study indicated that cross seetion of wood did not have a signifieant effeet on the rate of ınoisture contents inerease, but the efTeet of thickness and the EMC of the environınent on the rate of ınoisture eontents inerease were signifieant.