In the title compound, [Co(C(4)N(3))(2)(C(10)H(8)N(2)O(2))]·2H(2)O, a novel tricyano-methanide complex, the Co(II) atom is located on an inversion center and has a distorted octa-hedral coordination with two 2,2'-bipyridyl dioxide (dpdo) mol-ecules and two trans tricyano-methanide (tcm) anions. The equatorial plane is formed by the four O atoms of the two chelating dpdo ligands, with one N atom of each of the two tcm ligands occupying an apical position. There is a disordered solvent water mol-ecule in the asymmetric unit (occupancy ratio 0.63:0.37). These water mol-ecules result in the formation of O-H⋯O and O-H⋯N hydrogen bonds, building a layer parallel to (100). The layers are linked by C-H⋯N hydrogen-bonding inter-actions, leading to a three-dimensional network.