Magnesium iron hexahydride is an inorganic compound with the formula Mg2FeH6.

The material is prepared by heating a mixture of powdered magnesium and iron under high pressures of hydrogen:[1] The compound is isomorphous with K2PtCl6, i.e., their connectivities and structures are the same.

The [FeH6]4− centre adopts octahedral molecular geometry with Fe-H distances of 1.56 Å.

The Mg2+ centres are bound to the faces of the octahedron, with Mg-H distances of 2.38 Å.

Measurements on such compounds suggest that the hydride ligand exerts a weaker crystal field than cyanide.