We report the electronic structure of methyne boron buckyballs B-68(CH)(12), B-72(CH)(8) and B-76(CH)(4) obtained by substituting, respectively, 12, 8 and 4 boron cap atoms by methyne CH groups on the boron buckyball B-80. DFT calculations and minimization techniques have been employed to characterize the structural and electronic properties of endo and exo isomers of these molecules in T-h and T symmetry. A vibrational frequencies analysis predicts that only endo-B-72(CH)(8) and endo-B-76(CH)(4) correspond to a true minimum on the potential energy hypersurface with a cohesive energy similar to the boron buckyball. The stable substitutions are characterized by six rhombohedral B-4 bonding motifs. (C) 2009 Elsevier B.V. All rights reserved.