In order to obtain fine mullite powders by a simple and inexpensive processing route gamma alumina (gamma-Al2O3) is used as raw material, and the heterogeneous nucleation-and-growth process is chosen. Composite coating particles consisting of gamma-Al2O3 cores with outer homogeneous amorphous silica layer are prepared by the heterogeneous nucleation-and-growth process in the ethanol suspension containing ammonia, tetraethylorthosilicate (TEOS) and gamma-Al2O3. Ultrafine mullite powders (average particle size of 0.63 mum) were fabricated by calcined composite coating particles at 1400degreesC for 2 h. (C) 2002 Elsevier Science B.V. All rights reserved.