Small-diameter ZnO nanorods have been prepared from aqueous solution containing Zn(OH)(4)(2-) ions, manganese acetate, and sodium dodecyl sulfate in 3 h at room temperature. The added Mn2+ ions are considered to lead to the formation of MnO2 nanoparticles, which serve as the nucleation sites, to facilitate the growth of small diameter ZnO nanorods. The as-prepared ZnO nanorods are single crystalline, 7-10 nm diameter and 200-300 nm in length. The high surface-to-volume ratios determined by the Brunauer-Emmett-Teller method and the surface oxygen deficiencies suggested by the cathodoluminescence spectrum for the ZnO nanorods are conductive to the photocatalytic activity. The photocatalytic activities on the conversion of nitride oxides and degradation of methylene blue by ZnO nanorods were found to be significantly enhanced by the presence of small-diameter ZnO nanorods. Because the small-diameter ZnO nanorods were synthesized in one step, with simple and inexpensive equipment at low temperature, they are promising for industrial applications. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3083221] All rights reserved.