MgAl2O4 spinel precursor was prepared using a heterogeneous sol-gel process. The effect of high-energy milling on the precursor decomposition and spinel formation was investigated. The milling decreased the Al(OH)(3) dehydroxylation temperature from 190 degrees to about 130 degrees C. The activation energy for spinel formation decreased from 688 kJ/mol for the as-prepared precursors to 468 kJ/mol for the precursors milled for 5 h. Milling of the precursor lowered the incipient temperature of spinel formation from 900 degrees to 800 degrees C, and the temperature of complete MgAl2O4 spinel formation from > 1280 degrees to similar to 900 degrees C.