The heavy crude oils with high percentage of organic acids and sulfur, which at high temperatures and flow rates, are corrosive in furnaces, towers and lines transfer distillation units. The corrosive effect of two heavy crude oils with different TAN (total acid number) on stainless steel 5Cr-1Mo, at three different temperatures, maintaining a rotating speed and pressure constants was studied. The tests were conducted in a dynamic autoclave suitable for high temperature, by using gravimetric analysis to determine the corrosion rate. The dependence of the corrosion with the total acid number (TAN) and the content of sulfur compounds were evaluated. Subsequently, samples were characterized by SEM and EDX where sulfur compounds were found in the layer formed.