An improved synthesis and a full characterization of all three 12-vertex C-hydroxydicarba-closo-dodecaboranes 1-3 are reported. These inorganic analogues of phenols are highly acidic, but unlike phenols, they are transparent in the near-UV region and are stable to oxidation. The structure of their oxyanions 1a-3a poses an interesting issue of a close versus a bridged nido form. Also described is an introduction of a functionalized spacer in position 2 of 1 designed to permit incorporation into more complex organic structures.