A chemical co-precipitation process was developed for the preparation of indium tin oxide (ITO) particles using a membrane dispersion micromixer with indium chloride, tin chloride and ammonia as the reagents. The traditional co-precipitation process make it hard to control the particle size in a beaker, and therefore a novel membrane dispersion micromixer, which could control particle size, was used. At the same time, the particle size was significantly reduced with improved mixing performance in the membrane dispersion micromixer. The effect of the pH value and concentrations of reagents solutions on the size of ITO particles were investigated. The particle size increased from 18 nm to 83 nm and the specific surface area decreased from 55.44 m(2)/g to 16.32 m(2)/g, respectively, where the pH value changed from 9.56 to 6.70. But the particle size decreased when the reagents concentrations were increased. Furthermore, the effect of the aging process on the crystal structure of ITO particles was investigated. It was proved that the aging process is beneficial for the preparation of cubic ITO particles, excluding hexagonal ITO particles. This study provides a size-controllable ITO preparation method to control particle size and enhance the cubic phase purity. (C) 2016 Elsevier B.V. All rights reserved.