Large-scale alpha-Fe2O3 porous nanorod array precursors with high-orientation have been successfully prepared using one-pot hydrothermal method without any template. Upon calcination, alpha-Fe2O3 porous nanorod arrays have been fabricated. Synthesized samples were characterized by X-ray diffraction, field emission scanning electron microscopy, (High-resolution) transmission electron microscopy and Thermal-gravimetric analyses. The feature sizes of the porous nanorods are around 20-30 nm in lateral direction and 110-120 nm in length. The longer axis direction, which is the growth direction of alpha-Fe2O3 nanorod arrays was determined to be [(1) over tilde2 0] by transmission electron microscopy. The effects of the reaction time, reaction temperature, and acetic acid on the morphologies of porous nanorod arrays were systematically investigated. A possible formation mechanism was proposed by orientation attachment. The synthesized alpha-Fe2O3 porous nanorod arrays exhibited a high adsorption capacity for the model organic pollutant of Methyl orange. Therefore, alpha-Fe2O3 porous nanorod arrays have a potential application in waste water treatment. (C) 2011 Elsevier B.V. All rights reserved.