The hot corrosion behaviors of Ni-16Cr-xAl(x=4.5, 6.8, 9.0, mass fraction) based alloys in Na 2SO 4-25 NaCl molten salts at 600 °C were investigated. The effects of pre-oxidation and Al content on the resistance to hot corrosion were examined. The hot corrosion resistance of Ni-16Cr-xAl based alloy with Al addition from 4.5 to 9.0 increases with increasing Al content. The alloy with Al content of 9.0 shows the highest hot corrosion resistance among the examined alloys because more β-NiAl phases are obtained to sustain the Al 2O 3 scale repaired during hot corrosion. Pre-oxidized specimens have a superior hot corrosion resistance compared with the as-cast specimens, due to a protective oxide scale formed after pre-treatment. © 2011 The Nonferrous Metals Society of China.