Single crystals A₂A'ReO₆ (A = Sr, Ba; A' = Li, Na) were grown by the high temperature flux method in silver tubes and crucibles. Yellow colored hexagonal shaped crystals were isolated from the respective alkali and alkaline earth hydroxide fluxes in sealed silver tubes and crucibles. The water soluble rhenates were isolated from the flux using methanol aided by sonication. Phase purity in each case was confirmed by powder X-ray diffraction. The crystal structures were determined by single crystal X-ray diffraction. All the compounds crystallize in the cubic double perovskite system, Fm-3m (a ~ 8.12 Å) consisting of alternating corner-sharing (Li/Na)O₆ and ReO₆ octahedra, with the A-cation occupying the 12 fold coordination site in the middle of a cube formed by 8 (Li/Na)O₆ and ReO₆ octahedra. The presence of Li in A₂LiReO₆ (A = Sr, Ba) was verified by ICP elemental analysis and further confirmed by 7Li NMR spectroscopy. The compounds undergo hydrolysis in water to form A₅A'Re₂O₁₂ (A = Sr, Ba; A' = Li, Na) which crystallizes in the hexagonal space group, P6₃/m, with a = 9.9772(3) Å, c = 18.9268(13) Å, V = 1631.64(13) ų and Z = 6. The crystal structure consists of layers of isolated ReO₆ octahedra separated by layers of SrO_x polyhedra. The LiO₆ octahedra are both face and edge shared with ReO₆ octahedra. The crystal growth and structural chemistry of these rhenium oxides will be presented.