The present study reports for the first time the use of biobased chitosan/polybenzoxazine (CTS/PBZ) as a precursor for high CO2 adsorbing carbon aerogels (CAs). Montmorillonite (MMT) is used to reinforce the CTS/PBZ aerogel. CTS/PBZ/MMT hybrid aerogels are synthesized using freeze-drying technique and then crosslinked via ring-opening polymerization of benzoxazine (BZ), followed by carbonization at 800 oC. Polybenzoxazine (PBZ) improves geometrical stability necessary for removing CO2 even at high pressure. The aerogels have been evaluated using X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The microstructure of the CAs is characterized by N2 adsorption/desorption measurements at -196 oC. The CAs exhibit micropores and high BET surface area. The total pore volume of CAs is as large as 0.296 cm3 g-1 and a maximum BET surface area of 710 m2 g-1. The performance of CO2 adsorption was determined by gravimetric method at different temperatures (25, 50, 75, and 100 oC) and pressures up to 1 atm. Breakthrough curves of CO2 adsorption show that the CAs provide excellent CO2 adsorption/desorption performance with a maximum adsorption capacity of 5.72 mmol g-1. Adsorption isotherms and thermodynamic properties of the CO2 adsorption have also been investigated. Keywords: Carbon aerogels; CO2; chitosan; polybenzoxazine; adsorption; and thermodynamics properties.