The microwave solvothermal reaction of nickel nitrate with trimesic acid provided the title compound, [Ni(3)(BTC)(2)(H(2)O)(12)](n) (BTC = benzene-1,3,5-tricarboxyl-ate anion, C(9)H(3)O(6)), which is a metal coordination polymer composed of one-dimensional zigzag chains. The crystal under investigation was ramecically twinned with an approximate twin domain ratio of 1:1. In the asymmetric unit, there are two types of Ni atoms. One of the NiO(6) groups (2 symmetry) is coordinated to only one carboxyl-ate group and thus terminal, the other is bridging, forming the coordination polymer. The extended chains are connected by the organic BTC anions via μ(2)-linkages. O-H⋯O hydrogen bonds and π-π inter-actions between the chains [centroid-centroid distance 3.58 (1) Å] induce the complex to mimic a three-dimensional structure.