Changes in free energy, enthalpy, and entropy were determined for sorption (desorption and adsorption) of water in wood. Findings were that changes are different for desorption and adsorption, have a strong dependence on moisture content, and have a weak dependence on temperature. Suggestive explanations are given for variation of energy changes during sorption with moisture content and temperature, and the differences in their values for desorption and adsorption are discussed. Studies on enthalpy-entropy compensation effect were made and a linear relationship is found to exist between enthalpy and entropy for both desorption and adsorption of water in wood.