Its icosahedral shape is consistent with the classification of this cage as "closo" in polyhedral skeletal electron pair theory.

Crystals of Cs2B12H12 feature Cs+ ions in contact with twelve hydrides provided by four B12H122−.

[3] The dodecaborate anion was first prepared in modest yield by Pitochelli and Hawthorne from iododecarborane.

First the borohydride is converted into a triborate anion using the etherate of boron trifluoride: Pyrolysis of the triborate gives the twelve boron cluster as the sodium salt, which is then treated with caesium hydroxide to precipitate Cs2B12H12.

[5] Salts of B12H122− have been investigated for boron neutron capture therapy and as fuels for airbags.