The Nb-NiTi eutectic alloys were directionally solidified (DS) in an optical floating zone furnace. Colunmar grains of eutectic structures containing rod-shaped Nb in the NiTi matrix is observed in the DS ingots irrespective of the alloy composition. Well-aligned rod-type eutectic microstructures can be obtained for samples with a composition of Nb-41Ni-40Ti grown at relatively slow growth rates below 2.5mm/h. The hydrogen permeability along the direction parallel to the Nb rods of Nb-41Ni-40Ti DS alloy grown at 1mm/h is 2.60x10(-8)mol H-2 m(-1) Pa-1/2 at 673K. which is over 20 times higher than that measured perpendicular to the Nb-rod direction. No hydrogen embrittlement is observed between 573 and 673K indicating that the eutectic structure itself is favorable in suppressing the hydrogen embrittlement of Nb.