Two two-dimensional and three-dimensional coordination-polymer, [Ni (2, 2', 5, 5'-bpdc) (H2O)]H2O (1) and[Ni (2, 2', 6 6'-bpdc) 2]-4H2O (2) were obtained via hydrothermal reaction between NiCl26H2O and 2, 2'-bipyridine-5, 5'-dicarboxylic acid (2, 2', 5, 5'-bpdc), 2, 2'-bipyridine-6, 6'-dicarboxylic acid (2, 2', 6, 6'-bpdc) respectively, and were characterized by infrared spectra, thermogravimetric analysis and single crystal X-ray diffraction. The 2, 2', 5, 5'-bpdc and 2, 2', 6, 6'-bpdc ligands in compound 1 and 2 show different coordination modes respectively. The 2, 2', 5, 5'-bpdc ligand act...