A standard X-ray source and an energy-sensitive detector were placed on both sides of a wood dryer which operates over a wide range of drying conditions. The spectrometric X-ray intensities transmitted through the wood sample were related to the mass concentration of wood and water using a rigorous calculation needed in the case of a polychromatic X-ray beam. The source and the detector are carried by a motion controller in order to scan the sample at different drying times and determine the moisture content (MC) profile along the board thickness. Treatment on spectrometric data and the evolution of the MC profiles in a Norway spruce board (Picea abies) are presented in this work.