The corrosion resistance of carbon steels in caustic-containing sulfide solutions depends on the formation of a stable passive film on the metal surface. As processes change chemical concentrations and temperature parameters, the corrosivity of the system also changes. New resistant materials such as duplex stainless steel are being selected for equipment in many processes, yet carbon steel continues to be utilized for a significant amount of new and existing equipment and can be subjected to conditions beyond the initial design parameters. The present study investigates the effects of temperature up to 170 C and of the concentrations of sulfide and hydroxide on the corrosion rate to determine environmental limits for the reliable operation of carbon steel A516-Gr70. The results indicate that carbon steel A516-Gr70 can exhibit high corrosion rates as the concentration of hydroxide or sulfide increases at temperatures above 100 degrees C and changes the open-circuit potential to values below -1.00 V (SCE).