Hot-dip silico-aluminized layers on commercial 310 stainless steel have been studied in a cyclic high temperature NaCl-containing environment. In the thermal cycling tests at 20 h intervals between room temperature and 850 degrees C with a 2 mg cm(-2) NaCl deposit on specimens in each cycle, the aluminized layers show good corrosion resistance during the first four cycles of testing, while degradation occurs after testing for five cycles. The reason for degradation of aluminized layers is attributed to the formation of interconnecting voids caused by aluminum inward diffusion, by chloridation/oxidation cyclic reactions and by the subsequent penetration of molten NaCl through the voids in the aluminized layer into the alloy substrate. Once the Al coatings crack open during testing, the corrosion morphology of alloy is similar to that observed in tests without coatings. (c) 2004 Elsevier B.V. All rights reserved.