The paper presents results of research on the possibility of producing T-joints of aluminium alloys without defect by friction stir welding process. Friction stir welding process is applied in welding T-joints of aluminium alloys 5052-H32 and 5754-H111. These relatively new welding tech-nologies produce high quality welded joints, where strength of the joint can reach the strength of the base material. Visual and macrostructural examination and microhard-ness measuring of the welded T-joints are processed
