The single crystals of perovskite fluorides (NH 4 ) 2 NaVF 6 and Na 3 VF 6 were synthesized under mild hydrothermal conditions. The structures of the compounds were determined by means of single-crystal and powder X-ray diffraction analyses, respectively. (NH 4 ) 2 NaVF 6 has a cubic elpasolite-type structure and crystallizes in the space group Fm3¯m with lattice constant a=8.495(0)Å. Rietveld refinement indicates that Na 3 VF 6 has a monoclinic structure and is in space group P2 1 /n. The compounds were characterized by scanning electron microscopy, thermogravimetric and differential thermal analysis, and variable temperature magnetic susceptibility. With the temperature decreasing, the magnetic studies of the compounds showed the magnetic ordering was related to the crystallographic features and isolated magnetic units.