Single-crystalline alpha-Fe2O3 nanorods with a polyhedral configuration have been successfully synthesized via a facile hydrothermal process at 180 degrees C. X-ray powder diffraction, transmission electron microscopy observations, field emission scanning electron microscopy, and selected area electron diffraction patterns were used to characterize the as-synthesized samples. The result reveals that goethite nanorods were first generated and then transformed into hematite via dehydration in the successive hydrothermal treatment, in which the alpha-Fe2O3 inherited the rod-like morphology of the goethite precursor. The effect of surfactant and treatment time on the phase and morphology of the final products has been studied, and a possible growth mechanism is proposed.