Solar power systems must be competitive with conventional energy sources in in terms of cost to make up a significant portion of the electric power grid.  Solar power can likely more rapidly grow and make-up a larger portion of the US power grid if systems have energy storage capability that could continue to provide power for extended periods without sunlight and vary the power as needed (i.e. – be dispatchable).  Concentrated solar power tower systems with thermal energy storage using advanced high operating temperature heat transfer fluids and advanced thermodynamic cycles can potentially meet the twin goals of low cost and high reliability while being dispatchable.  Molten salts are a promising candidate for a high operating temperature heat transfer fluids.  Due to the decomposition of molten nitrates at temperatures above about 550 °C, molten fluorides or chlorides are expected to be needed for higher temperature operation.  KCl-MgCl₂ is a promising  heat transfer fluid due to its low cost and good thermal transport properties.  Corrosion in molten chloride salts can be severe if salt chemistry is not well controlled.  Research has shown that the main corrosion mechanism in Fe-Ni-Cr alloys exposed to molten salts is selective oxidation of Cr and that the corrosion mechanism is mass transfer limited. In the research to be presented, thermosiphons were operated at three different temperature ranges to add flow to corrosion tests and evaluate changed  corrosion rates.  Four alloys were tested in the thermosiphons with varying temperature and with and without Mg redox control.  The most extreme case tested had the hot region at ~930 °C and cold region at ~880C.  The research found that naturally convective flow could increase up to 5 times the corrosion compared to static tests for Haynes-230 without corrosion inhibition.  Corrosion inhibition using Mg worked well to decrease corrosion and mass transfer reactions for Fe, Co, and Ni based superalloys.