Headline topic of this Master thesis is “testing of welded joint JR.03-DI.22. The introductory part of the Master thesis introduces and explains non-destructive testing methods, the advantages and disadvantages alligned with this method as well as the main use of the meantioned non-destructive method within industry. Furthermore, the trends in the development of non-destructive testing methods were described, with an emphasis on the automation of NDT processes and the characteristic errors that occur in welded joints. What is more, after the theoretical part of the Master thesis, the experimental part was conducted in collaboration with Dalekovod d.o.o. Within this part of the research, metal arc welding process was thoroughly described with the given example on the welded joint JR.03-DI.22. Lastly, applications of visual, ultrasonic and magnetic partical testing were examined and inspected on the previously mentioned welded joing. The examination was successfully conducted with NDT methods and the conclusion was formed based on given indications.