The term ''wood welding'', in the English language, designates what can be defined as the ''welding of
the wood''. This new process, that it provides the joint of wood pieces without the use of adhesives or any other additional material, provokes growing interest in the academic environment, although it is still in laboratorial state. Linear friction welding induced by mechanical vibration yields welded joints of flat wood surfaces. The use of this method provides connections that satisfy relevant requirements of the international norms. The phenomenon of the welding occurs in less time than 10 seconds, with the temperature in the rubbed surfaces reaching 170ºC, and the consequent change of state of the lignin and
hemicelluloses, that then melt and flow. The process results in the detachment of wood cells, and in a formation of a fibers entanglement network immersed in a matrix of molten material which then solidifies. X-ray micro densitometry exams and scanning electron microscopy (SEM) micrographs obtained shows a considerable density increment and a physic-chemical reorganization in the joints surfaces. This new composition of detachment wood cells/fibers of the two surfaces, a entanglement network immersed in a matrix of molten polymeric material, mainly melted lignin, yields in the interface of the welding a significant adhesion.