CO2 adsorption at elevated pressure was studied in a Mg-Al (Mg/Al = 3) layered double hydroxide (LDH). The double-layered structure was prepared via a coprecipitation method. The sample's structure and microstructure evolutions were characterized using X-ray diffraction, scanning electron microscopy, N-2 adsorption, and thermogravimetric and calorimetric analyses. The CO2 adsorption experiments were performed between 5 and 4350 kPa at different temperatures (30-350 degrees C). Elevated pressure experiments showed that this material was able to adsorb different quantities of CO2 depending on the thermal evolution of its structure and microstructure. The highest CO2 adsorption (5.7 mmol/g) was produced at 300 degrees C before the layered structure had completely collapsed. At these specific conditions the interlayer space was reduced from 7.78 to 4.39 angstrom. This interlayer change was attributed to the onset of LDH structural collapse. However, at this temperature the adsorption process must be favored over the adsorption-desorption equilibrium, allowing the maximum CO2 capture.