A combination of differential scanning calorimetry (DSC) and high resolution DTG coupled to a gas evolution mass spectrometer has been used to study the thermal properties of a series of Cu/Zn hydrotalcites of formulae CuxZn6-xAl2(OH)(16) (CO3).4H(2)O where x varied from 6 to 0. The effect of increased Zn composition results in the increase of the endotherms and weight loss steps to higher temperatures. Evolved gas mass spectrometry shows that water is lost in a number of steps. The interlayer carbonate anion is lost simultaneously with hydroxyl units. The endotherms and differential weight loss steps were both cation and mole ratio dependent.