Two new barium borate fluorides LiBa12(BO3)(7)F-4 and NaBa12(BO3)(7)F-4 are obtained by spontaneous crystallization from high-temperature flux. The two compounds are isostructural and crystallized into the tetragonal system, I4/mcm space group, with unit cell parameters of a = 13.5709(6) angstrom, c = 14.9908(13) angstrom for LiBa12(BO3)(7)F-4 and a = 13.6443(9) angstrom, c = 15.021(2) angstrom for NaBa12(BO3)(7)F-4. Isolated Li/NaF4-BO3 units formed by Li/NaF4O square pyramids and B3O(3) groups sharing the O5 atom are found occupying the octagonal tunnels built by Ba and BO3 groups along the c axis. High mobility of Li+ ion is observed in the LiBa12(BO3)(7)F-4 single crystal by ac impedance measurements at different temperatures.