In the title compound, [Co(H(2)O)(6)](C(14)H(10)O(6))·2H(2)O, the 2,2'-[naphthalene-1,8-diylbis(-oxy)]diacetate dianion L is not coordinated to the Co(II) ion. The asymmetric unit contains half of the L dianion, half of a [Co(H(2)O)(6)](2+) cation (both molecules being completed by inversion symmetry), and one water mol-ecule. The crystal packing features O-H⋯O hydrogen bonding between the carboxyl-ate groups, the aqua ligands and the hydrate water mol-ecules.