Ferrocenium tetrafluoroborate is an organometallic compound with the formula [Fe(C5H5)2]BF4.

This salt is composed of the cation [Fe(C5H5)2]+ and the tetrafluoroborate anion (BF−4).

The standard potential of ferrocene-ferrocenium is dependent on specific electrochemical conditions.

[2] Commercially available, this compound may be prepared by oxidizing ferrocene typically with ferric salts followed by addition of fluoroboric acid.

[4] According to X-ray crystallography, the structures of the metallocene component of FcBF4 and the parent ferrocene are very similar.