Nano- or submicron In(OH)(3) and In2O3 particles of different morphologies were synthesized from a nitrate solution by a homogeneous precipitation process. By using X-ray diffractometer, thermogravimetric analysis, transmission and scanning electron microscopes, and inductively coupled plasma-optical emission spectrometry, the properties of particle growth were analyzed. The results indicated that the kinetics of the hydrolysis reaction of In3+ was a zero-order reaction with an activation energy of 128 kJ/mol, which implied that the reaction was controlled by the decomposition kinetic of urea additive. The growth anisotropic of particles, pH value of reaction solutions, residual In3+ concentration relative to aging time with different temperatures and starting concentrations were reported in this study. Calcination of the hydrate to form In2O3 particles between 300 degrees and 900 degrees C did not greatly change the morphologies of the particles.