Bis(piperazine-l,4-diium) decabromodiantimonate(III) dihydrate, (C4H12N2)(2)[Sb2Br10]& DOT;2H(2)O, (abbreviated as PSB) has been synthesized and characterized by single-crystal X-ray diffraction studies. The obtained results indicate that PSB is isostructural with a recently described chloride analogue, (C4H12N2)(2)[Sb2Cl10]& DOT;2H(2)O (PSC), crystallizing with R2MX5 & DOT;nH(2)O stoichiometry and characterized by the discrete zero-dimensional anionic species. The crystal structure of PSB is described by monoclinic symmetry in a P2(1)/n space group. Dielectric measurements (down to 25 K) and IR spectral analyses (measured over a broad temperature range) suggested a much more complicated phase situation below 80 K than for that of PSC. To verify and compare the molecular motions of the organic cations in both analogues, a proton magnetic resonance (H-1 NMR) technique was also applied.