Mg-Al hydrotalcite (Mg6Al2(OH)16CO3·4H2O), the precursor of MgAl2O4 spinel, has been synthesized via a coprecipitation method, using AlCl3·6H2O and MgCl2·6H2O as the raw materials, and NaOH and Na2CO3 as the precipitators. The effect of the reaction temperature, from 50 oC to 90 oC, on the Mg-Al hydrotalcite nanocrystallites was analyzed. The nanocrystallites were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was confirmed that Mg-Al hydrotalcite nanocrystallites are pure and regularly hexagonal, having a typical hydrotalcite structure. The Mg-Al hydrotalcite crystals grow from about 30 nm to 100 nm with an increase in the reaction temperature from 50 oC to 90 oC, and the crystal form also tends to perfect and regularly hexagonal

Keywords: nano, Mg-A1 hydrotalcite, reaction temperature, coprecipitation, spinel.