Friction welding of wood is an innovative process, able to join pieces of wood without additional adhesives. Because of its hygroscopic properties, the wood matrix absorbs humidity at the surface from the surrounding atmosphere. Its moisture content is strongly dependent on ambient conditions and seasonal changes. Former research showed that after samples passed a certain moisture content threshold, the creation of welded wood-towood connections becomes difficult and shear strength is significantly reduced. Tests carried out on spruce samples with different moisture content should help to spot the limits of the materials moisture content, regarding the feasibility of establishing a welded wood-to-wood connection, but also to calculate which conditions lead to the most solid welded joints. If specific moisture content is needed to gain a satisfactory weld, this will have an impact on the storage conditions of the pieces to be welded.