Two {Ni-6} cluster-containing inorganic-organic hybrid compounds have been successfully synthesized in the presence of organic amine under hydrothermal conditions, and they were characterized by powder and single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, and IR spectroscopy. Structural analysis indicates that [Ni-0.5(H2O)(3)][{Ni-6(mu(3)-OH)(3)en(H2O)(10)}(H2P2W15O56)]center dot 10H2O (1, en = ethylenediamine) is a triangular inorganic {Ni-6} cluster substituted polyoxotungstate with only one en to stabilize the {Ni-6} cluster. However, [Ni(dap)(2)]{[Ni-1.5(dap)(1.5)(H2O)(3)][Ni-6(mu(3)-OH)(3)(dap)(2)(en)(H2O) {O2C(CH2)(2)CO2}(0.5)(CH3COO)(P2W15O56]}center dot 15H2O (2, dap = 1,2-diaminopropane) is a three-dimensional inorganic-organic hybrid compound linked by succinic acid. The magnetic properties of both compounds were studied. In addition, the adsorption properties of compound 2 have also been investigated.