The bidentate 1,3,4-thiadiazole ligand substituted by two 2-pyridyl rings (denoted L) has been found to produce the new monomeric title complex, [Co(C12H8N4S)2(H2O)2](BF4)2. The thiadiazole and pyridyl rings surrounding the Co atom are almost coplanar [dihedral angle = 4.35 (7)°]. The mean plane defined by these heterocyclic moieties makes a dihedral angle of 18.72 (6)° with the non-coordinated pyridyl ring. The Co2+ cation, located at a crystallographic center of symmetry, is bonded to two ligands and two water molecules in a trans configuration in an octahedral environment. The tetrafluoridoborate ions can be regarded as free anions in the crystal lattice. Nevertheless, they are involved in an infinite two-dimensional network along the [010] and [101] directions of O—H...F hydrogen bonds.