A simple and efficient alcohol thermal technique was applied to control the growth of the dimensions and morphology of ZnO nanostructures under mild conditions, where surfactant was not necessary. The size of ZnO nanocrystals increased with growth temperature and they transformed into nanorods with different aspect ratios through tuning the reaction time. The length of nanorods increased significantly with the reaction time, but their thickness only slightly increased. The as-prepared ZnO nanocrystals were monocrystalline and the growth orientation of ZnO nanorods was [001]. Photoluminescence measurements showed a blue shift in violet emission with a reduction in crystal size and revealed the quantum confinement effect. Electron irradiation induced structural damage was observed in the ZnO nanorods synthesized at 120 degrees C. Experimental results proved that the possible growth mechanism of ZnO nanostructures was oriented attachment.