Pivalic acid (Hpiv) is an attractive molecular building block in crystal engineering of discrete clusters and extended structures [1, 2] that combines the diverse coordination ability of carboxylic group with hydrophobic tert–butyl moiety. Surprisingly, but survey of Cambridge Structural Database (CSD) revealed only one example of coordination polymers based on pivalate mononuclear complexes where linear rod-like pyrazine ligand link the metals [3], but no one such complexes with 4.4′-bipyridine. This gap has encouraged us to undertake this research to shed light upon the possibility to obtain expanded structures in this system. Two new 1-D coordination polymers with composition [Co(piv)2(Hpiv)(pyz)(H2O)]n (I) and [Co(piv)2(4,4′bipy)(H2O)]n (II) (where 4,4′-bipy = 4,4′-bipyridine; pyz = pyrazine) have been synthesized from cobalt(II) pivalate [4] under hydrothermal conditions at 120ºC and structurally characterized. Both compounds crystallize in the monoclinic space group: I in P21/n, a = 18.338(1), b = 7.0741(4), c = 19.005(1) Å, β = 97.332(6); II in P21/c, a = 11.393(1), b = 11.407(1), c = 16.461(1) Å, β = 101.144(6)°. In the crystals I pyz spacer ligands coordinate in trans-positions and bridge Co(II) atoms in a linear polymer with Co···Co separation of 7.074 Å. The coordination surrounding of metal atom is completed up to N2O4 octahedron by two pivalate anions, one pivalic acid and water molecule, which all coordinate in a monodentate fashion. The O-H···O hydrogen bonds between the water molecule and pivalate ligand of neighboring chains result in the supramolecular ladder-like structure. The similar linear chains have been found in the crystals II, in which Co(II) atoms separated by 4,4′-bipy ligands and Co···Co distance equals 11.407 Å. Two piv ligands double bridge the neighboring center symmetry related chains in well defined ladder polymer with the shortest inter-chain Co···Co distance of 4.155 Å. The coordination octahedral N2O4 surrounding of the cobalt atom is provided by two piv bridges and chelate one.