In this study, resistance spot welding of steel sheets, which are widely used in the house-goods and car manufacturing industry, are studied. The investigations of tensile-shear strength, hardness and microstructure of the welded parts are carried out in order to find the effects of welding period and applied electrode force pressure. Welding periods are chosen as 5, 10, 15, 20 and 25 cycles, and applied electrode forces are increased from 3 to 6 kN. The welding current is kept constant at 5 kA. The samples are exposed to tensile-shear and hardness tests and metallographic examinations, and suitable welding parameters are advised to users. The results show that an increasing of both the welding period and the applied electrode force increase the tensile-shearing strength and hardness of the welding nugget.