The hydrothermal treatment of Ni(NO3)(2)center dot 6H(2)O, NaVO3, and Bpa (1,2-Di(pyridyl)ethane) (C12H12N2) at 120 degrees C during 3 days leads to green single crystals of the title compound. The single crystal X-ray diffraction reveals that [{Ni-3(H2O)(3)(Bpa)(4)}(V6O18)]center dot 8H(2)O crystallizes in the monoclinic system, P2(1)/c space group, with a = 13.5536 (2), b = 19.0463 (2), c = 27.7435 (3) angstrom, beta = 112.3880 (10)degrees, V = 6622(3) angstrom(3), with R1(obs) = 0.0558, wR2(obs) = 0.1359, for 10278 observed reflections. The complexity of the crystal structure is based on different points, as the existence of: both "gauche" and "trans" conformations of the organic ligand, the [V12O36](-12) cycles, formed by 12 corner-sharing VO4 tetrahedra, and, finally, the combination of both three-dimensional metal-organic and inorganic substructures, giving rise to a self-catenated highly connected net. The crystallization water molecules are semi-encapsulated in the channels along the [100] direction, and their loss gives rise to a dynamical and reversible structural contraction. Moreover, after the removal of the crystallization water molecules, the compound exhibits a negative thermal behavior in the 85-155 degrees C temperature range, and irreversible structural transformation due to the loss of coordinated water molecules up to 200 degrees C. The IR and UV-vis spectra were determined for the as-synthesized sample, after the removal of crystallization water molecules and after the irreversible transformation due to the loss of coordinated water molecules. The thermal evolution of chi(m) was adjusted to a magnetic model considering an isotropic dimer plus two Ni(II) d(8) isolated octahedra.