The aim of this master thesis was to perform the characterization of the welded joint of wear resistant steel grade Hardox 450. The properties of structural steels with improved wear resistance and their behaviour in exploitation were described in the theoretical part of the thesis. The welding of Hardox steels and the subsequent heat treatment of welded joints are described in detail. The results of the analysis of the chemical composition, microstructural analysis and testing of the mechanical properties are presented in the experimental part of the thesis. The analysed Hardox 450 steel contains about 0.2 % carbon and has a relatively fine-grained martensitic microstructure. Due to the high heat input during welding, in the heat-affected zone of the welded joint, the basic microstructure was disturbed, and the grain coarsening occurred. The fusion line is clearly defined, and the weld metal has a typical casting dendritic microstructure. Compared to the microhardness of the base material, which is around 430 HV0.2, the hardness in HAZ is lower and is approximately 250 HV0.2, while the lowest hardness is measured in the weld metal, around 210 HV0.2. Slightly lower HV10 hardness values were measured in the same areas. The tensile strength of the welded joint is significantly lower than the strength of the base material. During the bending test, no cracks appeared on the test samples at a bending angle of 180°. While testing fracture toughness, the heat affected zone had higher toughness than the weld metal.