In this paper, protonated titanate nanotubes (PTNTs) were modified with polyethyleneimine (PEI) by wet impregnation method for CO2 adsorption. Their micro-morphology and structural properties were characterized by a range of analytical techniques, including XRD, TEM, SEM, N-2 adsorption etc. Experimental results revealed that the functionalized PTNTs with 50 wt.% PEI loaded exhibited a high CO2 adsorption capacity of 130.8 mg/g-sorbent at 100 degrees C. Only a minor loss of its capacity was observed after five consecutive adsorption-desorption runs. The PEI was existed both in the internal and external mesoporous pores of PTNTs via chemical combination between amino group and enriched protons, which accounted for their good thermal stability at elevated temperatures. The results present herein imply that the PEI modified PTNTs could be appealing materials for capturing CO2 from power plant flue gas. (C) 2012 Elsevier Inc. All rights reserved.