DFT PBE0/cc-pVDZ method and the polarizable continuum model were used to determine pK _a values for buckminsterfullerene-acetylene hybrids C ₆₀HCCH, C ₆₀HCN, tert-butylacetylene, and propyne relative to tert-BuC ₆₀H in a vacuum, carbon disulfide, tetrahydrofuran, and dimethyl sulfoxide. The energies of the СH-acid molecule and the carbanion (fulleride- or acetylide anion) were calculated using the same number of Gaussian orbitals. The surfaces of cavities formed by molecules and anions in a solvent are composed of spheres encompassing both atomic nuclei and lone electron pairs. An additional sphere excludes the solvent from the inner cavity of the fullerene.