Nanometric/submicronic powders of magnesium indate spinel MgIn2O4 were prepared with a two-steps process. First, nano-oxides of In2O3 and MgO were obtained by combustion of aqueous solutions of metal nitrates (as an oxidizer) and different fuels (glycine/urea/citric acid). Then, the as-prepared combustion ashes were converted into pure spinels after calcinations at elevated temperature. The as-prepared powders spinels have nanometric or submicronic grain size. This process allows preparing the MgIn2O4 spinel compound in 1 day whilst 10 days were necessary when the classical solid state chemistry is used. In this paper, we compare these two ways and study the effect of different reaction parameters, such as the nature of fuels or the fuel/oxidiser ratio. Crystallites sizes of the synthesized compounds were investigated by powder X-ray diffraction and Scanning Electron Microscopy.