A new ternary titanium(IV) arsenate, CsTi2As3O12, has been synthesized by a flux method and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the cubic space group Ia3d (No. 230) with a = 20.495(3) Å, V = 8609(2) Å3, Z = 32, and R = 0.0242. The framework consists of vertex-sharing TiO6 octahedra and AsO4 tetrahedra, enclosing large cavities in which the cesium atom sites are partially occupied. The cavities are interconnected to form 3-dimensional channels. The structure is considerably different from those of NASICON and langbeinite.