Alkali-promoted aluminas are inexpensive and robust materials with significant basicity that allow CO 2 uptake at relatively high temperature and pressure. In situ XRD experiments show that bulk crystalline carbonate K-Dawsonite [KAlCO 3 (OH) 2 ] phase is formed on such materials under relatively high pressure of an equimolar mixture of CO 2 and steam (total pressure of 10 bar) and at temperatures up to 300°C. In parallel, typical needle-shaped Dawsonite crystallites are observed by SEM after exposure to similar conditions. Furthermore, the in-situ experiments show that the car-