In the structure of the title compound [Fe(2)(C(5)H(5))(2)(CHO(2))(CO)(4)]BF(4), each Fe(II) atom is coordinated in a pseudo-octa-hedral three-legged piano-stool fashion. The cyclo-penta-dienyl ligand occupies three fac coordination sites while the two carbonyl ligands and formate O atom occupy the remaining three sites.