A series of MgO aerosol nanoparticles were prepared by using a flame aerosol method and examined for the CO2 sorption at low-temperatures. Our XRD results suggest the formation of high purity magnesium oxide (MgO) phase. The CO2 sorption was determined at temperatures ranging from 60 to 275 degrees C using thermogravimetric (TGA) analysis, where the results indicate that the increased CO2 sorption we observed is associated with the improved pore volume and surface area of the sorbent. The as-synthesized MgO-A sorbent exhibited the best CO2 sorption capacity (66.0 mg CO2/g sorbent) at 60 degrees C in comparison with all of the sorbents tested. The CO2 uptake is predominantly controlled by the pore architecture as well as ultramicropores. The uptake characteristics of selected MgO sorbents we synthesized are significantly higher than that of CaO based sorbents at low temperatures.