In the title compound, {[Co(C(14)H(8)N(2)O(5))(C(10)H(8)N(2))]·3H(2)O}(n), the Co(II) cation is five-coordinated with a slightly distorted trigonal-bipyramidal geometry, and the 5-isonicotinamidoisophthalate ligands link Co(II) atoms into a layered structure. These two-dimensional arrays are further pillared by rod-like 4,4'-bipyridine ligands to give a three-dimensional framework with pcu (primitive cubic) topology. The magnetic and adsorption properties of the title compound are also discussed.