Sodium titanogallate, NaxTi2-xGa4+xO10 (x congruent-to 0.8), has been obtained as a new phase of a pseudo-ternary system of Na2O-TiO2-Ga2O3. The phase has a monoclinic system with cell parameters of a = 12.093(2), b = 3.0117(5) c = 10.4134(9) (angstrom) and beta = 92.29(1)degrees. Formation of NaTi2-xGa4+xO10 is limited to a small area of the composition-temperature diagram. The structure has been determined using the single-crystal X-ray diffraction technique. One-dimensional channels of octagonal cross-section extending along the b-axis, where sodium ions are located, are contained in the structure. The conventional Fourier syntheses revealed the distribution of sodium ions to be broadened along the channel axis. These facts suggest channels of this sodium titanogallate are promising for 1D conduction paths of sodium ions.