A facile microwave hydrothermal method for preparation of monodispersed barium titanate (BaTiO 3 ) nanocuboids with average size of 13 nm is developed, and the effects of synthesis parameters, such as molar composition of the precursor, synthesis time and temperature, on the morphology of BaTiO 3 nanocrystals are systematically evaluated. The resulting products are characterized by X-ray diffraction (XRD), Raman spectrum, infrared spectrum (IR), UV-vis diffuse reflectance spectrum, water contact angle, thermogravimetry (TG), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and selected area electron diffraction (SAED). A possible formation mechanism of BaTiO 3 nanocuboids is proposed. The BaTiO 3 nanocuboids show high photocatalytic activity for the degradation of Rhodamin B under UV irradiation.