The model of formation and growth of stoichiometric (Al2O3)n clusters during the combustion of aluminized fuels has been developed. In this model, the thermodynamic properties of large clusters (n=5-75) have been determined by matching the thermodynamic properties of small clusters n=2-4, calculated earlier by quantum-chemical methods, with similar characteristics of liquid droplets. The developed model was used for a numerical simulation of the formation of (Al2O3), clusters during the combustion a single aluminum particle with a diameter of 200 mu m in O-2/Ar atmosphere. It has been shown that, during the first 12 ms after the aluminum particle ignition, the rapid growth of clusters occurs. The mass of clusters in the combustion zone is comparable to the mass of aluminum oxide. The modeling results indicate that the growth of (Al2O3)n clusters can be the most probable mechanism of the formation of condensation nuclei of alumina. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.