The filling of carbon nanotubes with zinc oxide via wet chemical techniques is presented. Crystalline zinc oxide was introduced into carbon nanotubes by immersing empty and dried opened tubes in zinc nitrate solution followed by filteration and calcination, which was characterized by means of energy-dispersive X-ray spectroscopy and transmission electron microscopy (TEM). After burning off the carbon nanotubes at 75degreesC in air for 2 h, crystalline zinc oxide nanorods, with diameters in the range of ca. 20-40 nm and length of up to I mum, were formed, and characterized by powder X-ray diffraction (XRD). TEM and HRTEM. XRD indicated that the nanorods were hexagonal ZnO. (C) 2004 Elsevier B.V. All rights reserved.