Preparation of In2O3 nano-scale powders by ultrasonic and homogeneous precipitation, using metal In and urea as raw materials, was reported for the first time, while the effects of reaction temperature, the ratio of the materials and the pH etc. on the preparation was dicussed. This method can be operated and industrialized easily with very low cost. The structural properties of precursor and In2O3 were characterized by TG-DTA, XRD, ESCA and TEM. The results show that In2O3 produced are very pure, monophase and spherical nano-scale powders with average size of 25 nm.
