Resistance spot welding was used to joint AISI 316L austenitic stainless steel and AISI 1020 low carbon steel. During the welding process, temperature measurements were taken to obtain the temperature curves. Because of the different chemical compositions of the carbon steel and stainless steels, their thermal conductivity values are also different. Electrical resistivity is also an important parameter when carbon steel is spot welded to stainless steel. Differences in the thermal conductivity and in the electrical resistivity of metals lead to an asymmetrical weld nugget in the dissimilar joints. Dissimilar resistance spot welding can be more complex than similar welding due to different thermal cycle experienced with each metal.