Here we report the formation of iron in hexavalent state, Fe VI O 4 2 - in ozonalysis of iron(III) in alkaline medium. The formation of tetrahedral Fe VI O 4 2 - ion is confirmed by UV–Visible and Mössbauer spectroscopic techniques. The value of isomer shift, δ, of the tetra-oxy anion is consistent with known δ values for various salts of iron(VI) ion.