The stability of Mg(Al)O formed by calcination of Mg-Al-containing hydrotalcites has been studied under steam-rich conditions (H2O:N-2 = 1:1) at 600-650degreesC and 1 atm. It was found that the MgO structure as well as a high specific surface area are maintained after calcination at temperatures up to 800 C. It has further been observed that the steam stability of Mg(AI)O towards sintering is improved after calcination of hydrotalcite at higher temperatures: calcination at 800degreesC gave an improved stability of Mg(Al)O compared to calcination at 700degreesC. Further, the stability towards sintering was influenced by the Mg/Al ratio of the hydrotalcite. Mg(AI)O materials formed from hydrotalcites with a Mg/Al ratio of 5 exhibit better long-term stabilisation characteristics compared to a Mg/Al ratio of 3 after calcination at 800degreesC. A partial or full substitution of aluminum with gallium in the oxide did not improve the steam stability. Changing the hydrotalcite synthesis procedure from co-precipitation to the alkoxide route did not significantly alter the steam stability after calcination.