catena-Poly[[[tetraaquanickel(II)]-μ-4,4′-bipyridine-κ²N:N′] thiosulfate dihydrate], {[Ni(C₁₀H₈N₂)(H₂O)₄]S₂O₃·2H₂O}_n, (I), and catena-poly[[[tetraaquanickel(II)]-μ-4,4′-bipyridine-κ²N:N′] sulfate methanol solvate monohydrate], {[Ni(C₁₀H₈N₂)(H₂O)₄]SO₄·CH₄O·H₂O}_n, (II), are built up of {[Ni(4,4′-bipy)(H₂O)₄]²⁺}_n chains (4,4′-bipy is 4,4′-bipyridine) interwoven in an unusual P3₁ fashion. Voids are filled by the corresponding counter-anions and solvate molecules, defining a complex three-dimensional network surrounding them. In both structures, the cationic chains evolve around a set of twofold axes passing through the Ni^II ions and bisecting the aromatic amines through their N (and their opposite C) atoms.