ZnO nanobarbed fibers (NBFs) are synthesized by the epitaxial growth of 1-D ZnO nanorods (NRs) on ZnO nanofibers (NFs) via electrospinning and chemical bath deposition. The change in resistance of the NBFs in the presence or absence of a gas was explained using the surface depletion model and modified grain boundary model, in which the junction points of the NFs and NRs are considered. The NBF structure showed extraordinary NO2 sensing performance for gas concentrations up to 30 ppb. This indicates that NBF structures have great potential for use as gas sensing materials. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3590202]