The paper deals with the optimization of parameters of resistance spot welding and quality analysis of welded joints made of combination of galvanized steel sheets TRIP RAK 40/70+Z100MBO and DX51D + Z (EN 10142/2000 ). It is an advanced material combination frequently used in designing car body parts. The welded joints with various welding parameters were prepared. The quality of welded joints was evaluated by non-destructive and destructive tests. For evaluation of joints quality the shear tension test on spot joints according to STN 05 1122 standard was used. Some samples were prepared for metallographic analysis where the influence of the welding parameters on the structure of welded joint was observed. The influence of welding parameters on the dimensions of the weld nugget, and the occurrence of pores in the weld metal caused by evaporation of zinc from the coating were observed as well. Hardness was evaluated on metallographic scratch patterns according to STN EN ISO 14271 standard.