Microstructures of NaV2O5 prepared using flux method were characterized. These structures were observed to be dominated by lamellae with an average thickness of similar to 1 micron. These lamellae share (001) plane and stack along [001] direction. A small orientation difference among these lamellae was detected with electron diffraction to be within several degrees. A pure twist boundary with (001) plane as the boundary interface and high sigma value of 235 was determined. Within the lamellae there are numerous dislocations arranged parallel to the twist boundary. The twist boundaries and dislocations may introduce distortion in the layers of VO5 pyramids, which is believed to be unfavorable for Na atoms to position between these layers and may result in non-stoichiometry locally at the boundary. (C) 2005 Springer Science + Business Media, Inc.