The formation of magnesium spinel through a solid state reaction was studied. The synthesis was produced by mixing reactant powders in different proportions and after thermal treatments at 950 degrees C from 1 h to several days. The effect of LiCl on the kinetics of spinel formation was analysed. The mono-charged Li+ ion produces a deficient alumina and magnesia structure that accelerates the diffusion of Mg2+ and Al3+ into the respective oxides. The formation of spinel occurs into alumina particles. Transport through the gaseous phase of lithium and magnesium chlorides enhances the kinetics of production of magnesium aluminate. (C) 2005 Springer Science + Business Media, Inc.