The study of calcination treatment at 450°C on Ca-Mg-Al-hydrotalcite from brine water has been investigated. Characterization by XRD shows that Ca-Mg-Al hydrotalcite compound has found hydrotalcite phase and another phase such as Mg(OH)2, Al(OH)3 and CaCO3. These results are confirmed by the presence of hydroxyl groups, M-O and M-OH groups (M is Mg, Ca and Al) at wavenumber region around 3464.35 cm-1, 447.50 cm-1 and 531.41 cm-1. The calcination effect on Ca-Mg-Al hydrotalcite compounds at 450ºC being led to changes in structure become an metal oxide such as MgO, CaO, Al2O3, MgAl2O4 and CaCO3. These results are confirmed from decreasing on the absorption peak of M-OH group at wavenumbers region around 531.41 cm-1 and 786.99 cm-1 and widening of the absorption region at 500-900 cm-1. Consequently, the calcination treatment successfully increased the surface area of Ca-Mg-Al hydrotalcite compounds from 97.4 m2/g to 156.826 m2/g. Morphology of Ca-Mg-Al hydrotalcite changes the shape from a big to be small shape and the particle size distribution of 0-0.25 μm into 0-1 μm. Thermal analysis showed changes in the structure of hydrotalcite into oxide begins at a temperature of 265°C and started to become oxide completely after the temperature reaches 428°C.