Single crystals of two new osmium-containing triple perovskites, Ba3LiOs2O9 and Ba3NaOs2O9, were grown from reactive molten hydroxide fluxes in sealed silver tubes. They crystallize in the space group P6(3)/mmc with lattice parameters of a = 5.8025(1) Angstrom, c = 14.1468(4) Angstrom for Ba3LiOS2O9 and a = 5.8858(1) Angstrom, c = 14.3451- (5) Angstrom for Ba3NaOs2O9. The magnetic susceptibility of these osmates indicates significant Os-Os coupling within the octahedra pair.