Decamethylferrocene or bis(pentamethylcyclopentadienyl)iron(II) is a chemical compound with formula Fe(C5(CH3)5)2 or C20H30Fe.

It is a sandwich compound, whose molecule has an iron(II) cation Fe2+ attached by coordination bonds between two pentamethylcyclopentadienyl anions (Cp*−, (CH3)5C−5).

It can also be viewed as a derivative of ferrocene, with a methyl group replacing each hydrogen atom of its cyclopentadienyl rings.

[5] This compound is a yellow crystalline solid that is used in chemical laboratories as a weak reductant.

In contrast, a tilt angle of 17° between the Cp* rings is observed in the crystal structure of the SbF−6 salt.