A series of supported MgO/gamma-Al2O3 composites (denoted as Mg/Al-x) with enhanced adsorption performance towards CO2 were successfully synthesized via a facile one-pot cation-anion double hydrolysis approach. Their phase structures, morphologies, textural properties and basic properties were comparatively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDX), N-2 adsorption-desorption, in situ diffuse reflection infrared Fourier transform spectroscopy (DRIFTS) and CO2 temperature programmed desorption (CO2-TPD). Three kinds of carbonates including bicarbonate, bidentate and monodentate carbonate are formed during the adsorption process, indicating a synergistic adsorption mechanism for CO2. For the dynamic CO2 adsorption without water vapor, the adsorption capacity decreases in the order of Mg/Al-0.2 > Mg/Al-0.3 > Mg/Al-0.1 > Mg/Al-0, which coincides with the trend of the amount of basic sites; especially, Mg/Al-0.2 with the Mg/Al molar ratio of 0.2 shows a stable adsorption capacity of 1.60 mmol/g without loss after 11 cycles at 60 degrees C. Furthermore, water vapor shows a positive effect on their adsorption, and Mg/Al-0.2 reaches an adsorption capacity of 2.10 mmol/g for the simulated flue gas with 10 vol% water vapor at 60 degrees C. Its relatively high adsorption capacity, excellent cyclic adsorption/desorption stability and facile preparation process make it an attractive candidate for CO2 capture with flue gas conditions. (C) 2016 Elsevier B.V. All rights reserved.