In this work, multi-walled carbon nanotubes impregnated with polyethyleneimine (MWCNT/PEI) have been prepared by wet-impregnation method with various PEI loadings for CO 2 capture. The surface features and morphology were observed by scanning electron microscopy (SEM) and the textural properties were analyzed by N 2 /77 K adsorption–desorption isotherms. The CO 2 adsorption capacity was evaluated by thermogravimetric analysis (TGA) method at 15% CO 2 partial pressure. The MWCNT/PEI exhibited higher CO 2 adsorption capacity than pristine MWCNTs. This result suggested that amine groups were attached on carbon surfaces in the impregnation process, leaving CO 2 affinity sites on MWCNT surfaces. MWCNT/PEI exhibited superior cycle stability for CO 2 capture, indicating great potential for application in post-combustion technology.