Titanium oxalate was precipitated by the addition of TiO(NO3)(2) solution to an ethanol solution of oxalic acid and then ripened in the mother solution with/without ultrasound at various temperatures. The influence of various factors such as reaction temperature and ripening time, as well as the effect of ultrasonic treatment in the solution, was investigated. During the ripening reaction of the titanium oxalate, a new crystalline phase was found. The chemical formula and the crystal system of the new phase were as follows: (1) Chemical formula-Ti2O2(C2O4)(OH)(2)H2O, (2) Crystal system-orthorhombic with lattice constants of a = 1.0503 nm, b = 1.5509 nm, and c = 0.9700 nm. The treatment of ultrasound during the ripening reaction accelerated the dissolution rate of the initial precipitated particles, so that the formation of the crystalline phase was hastened.