Welding is an inevitable way of joining materials in mechanical engineering, the execution of construction elements, and in chemical, petroleum and petrochemical industry plants. The aim of this thesis was to examine the corrosion resistance of various samples of welded joints of structural steel S355 depending on the method of preparation, mechanical processing and surface preparation and their protection. In order to analyze the corrosion resistance of the welded joints in the experimental part of the work, a 168-hour test was carried out in a salt chamber according to the CCT-1 cyclic corrosion test standard. Furthermore, penetrant tests were carried out for a better understanding of the occurrence of corrosion and the determination of potential corrosion outbreak sites, as well as the Cross-Cut method. The results after subjecting the experiment to the influence of the salty atmosphere in the salt chamber indicate that there is no difference between samples of cleaned and uncleaned surfaces, if they are not protected by coatings. Samples with a primer and a topcoat show high resistance in a salty atmosphere with better adhesion of samples containing both a primer and a topcoat. The salt chamber did not have a big impact on Cross-Cut test, and all coatings show very high adhesion to the metal surface.