The title compound, for which crystals are more reactive toward oxygen than the chemically similar compound VSO4.6H(2)O, has been prepared as large single crystals and characterized by both X-ray diffraction at room temperature and neutron diffraction at 11-16 K. VSO4.7H(2)O crystallizes in the monoclinic space group P2(1)/c, Z = 4, with the following cell dimensions, where in each case the room temperature X-ray value is given first followed by the 11-16 K neutron value : a = 14.130(3), 14.013(2) Angstrom; b = 6.501(1), 6.481(1) Angstrom; c = 11.017(2), 10.981(2) Angstrom; beta = 105.64(2), 105.39(1)degrees; V = 974.5(3), 961.5(3) Angstrom(3). The structure was refined to residuals of R = 0.0289 and 0.0766 and quality of fit = 1.047 and 1.427 for X-ray and neutron data, respectively. It consists of two independent centrosymmetric V(H2O)(6)(2+) ions connected to a sulfate ion and an interstitial water molecule by an extensive network of hydrogen bonds. The room temperature and low-temperature structures are qualitatively identical. Each hydrogen atom is involved in a hydrogen bond. The network of hydrogen bonds is implicated in the stability of VSO4.7H(2)O in the solid state in dry surroundings.