Tetraborate pillared Li-Al layered double hydroxide was synthesized for the first time by a mechano-hydrothermal process in which gibbsite (Al(OH)(3)) sample was first activated by a ball milling, followed by hydrothermal treatment with Li2B4O7 in water at 95 degrees C. Activation of gibbsite Al(OH)(3) induced by mechanochemical process was essential for the formation of thin disk-like Li-Al LDH intercalated with borate anion. When in excess the activated Al(OH)(3) was transformed into bayerite phase during the hydrothermal process.