[en] ZnO nanowires (NWs) and ZnO nano-sheets were grown using the chemical vapor deposition method. The NW structure was characterized using transmission electron microscopy, while the mean inner potential and inelastic mean free path for 200 keV electrons were measured using off-axis electron holography to be 15.3 ± 0.2 V and 55 ± 3 nm, respectively. These values were then used to characterize the thickness of a ZnO nano-sheet, and gave consistent results. This study demonstrates that electron holography can provide useful information about nanostructured ZnO materials and devices. (paper)