ZnO nanorods were grown by catalyst-assisted vapor phase transport on Si(001), GaN(0001)/c-Al2O3, and bulk ZnO(0001) substrates. Morphology studies as well as X-ray diffraction and transmission electron microscopy showed that ZnO nanorods grew mostly perpendicular to the GaN(0001) and ZnO(0001) substrate surface, whereas a more random directional distribution was found for nanorods on Si(001). Comprehensive optical properties of nanorods were studied by steady-state photoluminescence and time-resolved photoluminescence. Stimulated emission was observed from ZnO nanorods on GaN(0001)/c-Al2O3 substrates, most likely due to their vertical orientation. Near-field scanning optical microscopy was applied to investigate luminescent properties of individual rods. Raman spectroscopy revealed biaxial compressive strain in the nanorod samples grown on Si(001). The strain magnitude was reducing with increasing length of the nanorods. Conductive atomic force microscopy showed that nanorods are electrically isolated from each other. I-V spectra of individual nanorods were measured.