A highly symmetric Mn^IV-centered polyoxoniobate [H₂Mn^IVNb₁₀O₃₂]⁸⁻ was synthesized via hydrothermal methods as a soluble tetramethylammonium salt. The structure is similar to decatungstate structure [W₁₀O₃₂]⁴⁻, except for the central heteroatom. The cluster is stable between 4 < pH < 10, as was characterized with ESI-MS and UV-Vis spectroscopy.