Abstract The corrosion behavior of AISI 304 and 316 stainless steels (SSs) in hot concentrated caustic soda solutions was investigated under heat-transfer conditions. The corrosion potential of the specimens was located in the active region; thus, the alloys were attacked in the form of general corrosion, depending on the heat-transfer conditions. AISI 316 was more susceptible than AISI 304. Such corrosion behavior is attributed to the failure of the passive film on the heated surface, caused by concentration of caustic solution next to the metal surface and erosion by gas bubbles. A molybdenum-free alloy, AISI 305J1, was tested under the same conditions as AISI 316 to clarify the detrimental effect of Mo on austenitic SS corrosion in hot concentrated NaOH. Intergranular corrosion was occasionally found when the potential was located in the passive region, depending on test conditions and heat treatment of the specimens.