The Letter concerns an investigation of CO2 flow through narrow carbon nanotubes (CNTs) at room temperature and the effects of CNT defects on CO2 diffusion. molecular dynamics (MD) simulations have been carried out for (6,6) and (8,8) CNTs, with Carbonyl groups being used as defects in the nano-structures. Different loadings have been investigated in connection with the transition mechanisms. The results show that both the different degrees of loadings and the presence of defects influence the diffusion mechanisms of CO2 through narrow CNTs. (C) 2014 Elsevier B.V. All rights reserved.