Photocatalytically active zinc oxide nanocrystalline rods are grown on high surface area polybutylene terephthalate (PBT) polymer fiber mats using low temperature solution based methods, where the oxide crystal nucleation is facilitated using conformal thin films formed by low temperature vapor phase atomic layer deposition (ALD). Scanning electron microscopy (SEM) confirms that highly oriented single crystal ZnO nanorod crystals are directed normal to the starting fiber substrate surface, and the extent of nanocrystal growth within the fiber mat bulk is affected by the overall thickness of the ZnO nucleation layer. The high surface area of the nanocrystal-coated fibers is confirmed by nitrogen adsorption/desorption analysis. An organic dye in aqueous solution in contact with the coated fiber degraded rapidly upon ultraviolet light exposure, allowing quantitative analysis of the photocatalytic properties of fibers with and without nanorod crystals present. The dye degrades nearly twice as fast in contact with the ZnO nanorod crystals compared with samples with only an ALD ZnO layer. Additionally, the catalyst on the polymer fiber mat could be reused without need for a particle recovery step. This combination of ALD and hydrothermal processes could produce high surface area finishes on complex polymer substrates for reusable photocatalytic and other surface-reaction applications. (C) 2011 Elsevier B.V. All rights reserved.