The topic of this thesis is the analysis of welding technology of the austenitic steel X2CrNiMo17-12-2. The paper is divided into two parts, theoretical and experimental. In the first part of the thesis, the theoretical part, the basic characteristics of high-alloy austenitic stainless steels are presented. Changes in the microstructure during welding and the influence of individual welding parameters are described. Furthermore, individual welding technologies applied to austenitic steels with emphasis on thicker wall constructions are described. Suitable filler materials and shielding gases for certain welding technologies are listed. The effects of preheating temperature, interpass temperature, and subsequent heat treatment to prevent deformations and the occurrence of critical microstructural phases are described. High - efficiency welding processes are also compared with conventional processes when welding thick - walled austenitic stainless steels. In the experimental part of the paper, based on the implemented welding technology of austenitic steel X2CrNiMo17-12-2, thickness 60 mm, the influence of welding parameters on the microstructure of the welded joint through the entire thickness of the material is analyzed in detail. Also, the mechanical properties were analyzed and a critical review of the welding technology and the results achieved was given.