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The current work investigates the hot corrosion demeanour of Hastelloy X weldment produced with autogenous mode through key-hole plasma arc welding (K-PAW). The hot corrosion test has been performed for weldment in molten salt-1 (MS-1) (75 % Na2SO4 + 25 % V2O5) and molten salt-2 (MS-2) (75 % Na2SO4 + 20 % V2O5 + 5 % NaCl) circumstance for 25 hrs (25 cycles) at 900 °C. The MS-1 substrate of both base metal and weldment provided the lowest weight gain than the MS-2 substrate. The NaCl in the MS-2 causes severe hot corrosion on the substrate, whereas the absence of NaCl in MS-1 reduces the hot corrosion effects. The highest parabolic constant is observed for K-PAW weldment in MS-2 condition. The tendency of hot corrosion rate follows the order of, Base Metal MS-1 < K-PAW MS-1 < Base Metal MS-2 < K-PAW MS-2. The occurrence of protective phases like chromium oxides (Cr2O3), spinel oxides (NiCr2O4 and NiFe2O4) Nickel oxide (NiO) on the substrate resist the further oxidation.