Corrosion behaviors of pure Ni and three NiCr alloys were investigated in an HCl-containing oxidizing atmosphere at 700 ℃ and 800 ℃. All materials suffer from accelerated corrosion at both temperatures. NiCr alloys show an initial mass loss due to the formation of volatile CrCl_3 and CrO_2Cl_2. Some chlorides are detected at the scale/substrate interface and many voids are also found there. NiCr alloys with higher chromium content have better corrosion resistance. However, Ni50Cr is inferior to Ni25Cr due to its two-phase structure, which makes it easy for chlorine to diffuse along grain boundary and to occur inner oxidation. The relevant corrosion mechanism was also discussed. Corrosion behaviors of pure Ni and three NiCr alloys were investigated in an HCl-containing oxidizing atmosphere at 700 ° C and 800 ° C. All materials suffer from accelerated corrosion at both temperatures. NiCr alloys show an initial mass loss due to the formation of volatile CrCl_3 and Some of the chlorides are detected at the scale / substrate interface and many voids are also found there. NiCr alloys with higher chromium content have better corrosion resistance. However, Ni50Cr is inferior to Ni25Cr due to its two-phase structure, which makes it easy for chlorine to diffuse along grain boundary and to occur inner oxidation. The relevant corrosion mechanism was also discussed.