In the crystal structure of the title compound, [Co(C(12)H(8)N(2))(3)](BF(4))(2)·CH(3)CN, the mol-ecular packing involves dimers of distorted octahedrally coordinated cations which are held together by one π-π [centroid-centroid = 3.542 (4) Å] and two C-H⋯π inter-actions [2.573 (4) Å] resulting in a P4AE (Parallel Fourfold Aryl Embrace) motif. The anions are found in aryl boxes formed from the phenanthroline ligands.