A simple hydrothermal route, using cetyltrimethylammonium bromide (CTAB) as the surfactant, has been proposed for synthesizing single-crystalline spinal cobalt ferrite (CoFe2O4) nanorods. Transmission electron microscope (TEM) and scanning electron microscopy (SEM) images indicated that the final product consists of nanorods with a diameter of about 25 nm and length up to about 120 nm. Furthermore, high-resolution TEM (H RTEM) revealed a clear lattice structure of the [100] planes in the nanorods. The magnetic properties of the CoFe2O4 nanorods were characterized using vibrating sample magnetometer (VSM). The possible formation mechanism for the CTAB-assisted hydrothermal synthesis of CoFe2O4 nanorods has been discussed. (C) 2004 Elsevier B.V. All rights reserved.