Nitrogen-doped (N-doped) single wall nanotubes (SWNTs) have recently been shown to have good catalytic reactivity towards oxygen reduction reaction (ORR). We used density functional theory calculations to explore reaction paths for facile oxygen dissociation on modified SWNTs, including nitrogen doping, Stone-Wales (SW) defects, and a combination of these two. It was found that oxygen dissociation is facilitated on carbon atoms neighboring a nitrogen dopant, with the dissociation barrier reduced from 2 eV to 0.68 eV. The activation barrier can be further reduced to 0.03 eV in the vicinity of a N-doped SW defect. The reduction in barrier height is explained through the local density of states analysis. (C) 2010 Elsevier B.V. All rights reserved.