The title compound, [Co(C(10)H(8)N(2))(3)]Cl(3)·4H(2)O, contains discrete [Co(bpy)(3)](3+) cations (bpy is 2,2'-bipyridine), Cl(-) anions and water mol-ecules. The [Co(bpy)(3)](3+) complex cation exhibits C(2) symmetry with the twofold axis through the central Co atom and bis-ecting one bpy ligand and one of the Cl(-) anions. The four solvent water mol-ecules and the remaining two Cl(-) anions lie on a mirror plane. Hydrogen-bond inter-actions define a two-dimensional layer structure parallel to (100), which consists of seven-membered [Cl(2)(H(2)O)(5)], eight-membered [Cl(4)(H(2)O)(4)] and ten-membered [Cl(2)(H(2)O)(8)] rings.