By using natural brucite and Al(OH)(3) as the starting materials, the Mg-Al layered double hydroxides (Mg-Al-CO3-LDHs) have been successfully synthesized via a simple hydrothermal strategy. The effect of hydrothermal synthesis temperature and reaction time on the crystal structure, grains size and Mg/Al molar ratios of Mg-Al-CO3-LDHs were investigated. The results showed that the cell parameters and Mg/Al molar ratios of the Mg-Al-cO(3)-LDHs increase when the hydrothermal reaction temperature increases from 140 degrees C to 180 degrees C. The size of crystal grain parallel to the direction of the layer D-1 1 0 is roughly constant, while the size of crystal grain in the vertical direction of the layer D-0 0 3 increases and D-1 1 0/D-0 0 3 decreases with the increment of hydrothermal reaction temperature. (c) 2012 Elsevier Ltd. All rights reserved.