In the title compound, [Co(C(12)H(15)O(4))(2)(H(2)O)(2)](n), adjacent Co(II) atoms ( symmetry) are bridged by 3-carboxy-adamantane-1-carboxyl-ate anions, forming a chain running along [001]. Inter-chain O-H⋯O hydrogen bonds link the chains into layers parallel to (100); the layers are further connected via inter-layer hydrogen bonds inter-actions, forming a three-dimensional framework.