The mechanochemical activation of a high defect kaolinite has been studied using a combination of high-resolution thermoggravimetry and DRIFT spectroscopy. The effect of grinding causes a decrease in the dehydroxylation temperature and an increase in the amount of adsorbed/coordinated water. The temperature of dehydration also increases with grinding time. It is proposed that this dehydroxylation occurs through a homogenous process involving proton transfer through point heating. The amount of adsorbed water decreases with the increase in temperature of the thermal treatment. (C) 2003 Elsevier Science B.V. All rights reserved.