Fluoro and oxyfluoro complexes of iron and vanadium were prepared using KHF2 and their thermal behavior was studied using TG/DTA techniques. All the three oxides of iron reacted with the cubic phase of KHF2, giving identical products, namely (NH4)(3)FeF6.1.5H(2)O irrespective of oxidation state of iron. KHF2 in its tetragonal, as well as cubic phases reacts with vanadium oxide depending on the molar ratio of the reactants. A possible pathway for the thermal degradation is given for the above complexes and the residues obtained were identified.