Octaborane-12 has been found to be a strong monobasic Lewis acid; several compounds of the type B8H12·L were prepared. Octaborane-12 was nearly quantitatively converted to hexaborane-10 by limited hydrolysis and in about 45% yield to n-nonaborane-15 by diborane. A new octaborane, octaborane-14, was prepared from octaborane-12 in a two-step conversion. © 1968, American Chemical Society. All rights reserved.