The asymmetric unit of the title compound, [Mo(C(18)H(24)N(2))(3)][Mo(6)O(19)]·4CH(3)CN, comprises an [Mo(di-t-Bu-bipy)(3)](2+) cation (di-t-Bu-bipy is 4,4'-di-tert-butyl-2,2'-bipyridine), two halves of Lindqvist-type [Mo(6)O(19)](2-) anions (with each anion completed by the application of a center of inversion) and four acetonitrile solvent mol-ecules. The geometry around the metal atom of the cation resembles a distorted octa-hedron, with each of the three di-t-Bu-bipy ligands being almost planar [deviation from planarity < 6.3 (2)°]. Supra-molecular inter-actions, namely Mo=O⋯π, C N⋯π, C-H⋯O and C-H⋯N, along with electrostatic forces, mediate the crystal packing. Two of the tert-butyl groups are affected by rotational disorder which was modeled over two distinct positions with major site occupancies of 0.707 (9) and 0.769 (8).