Ho(OH)(3) nanostructures were synthesized via a new facile hydrothermal reaction between Ho (NO3)(3)center dot 6H(2)O and tetraethylenepentamine (tepa) as novel precipitator in presence of bis-(2-hydroxy-1naphthaldehyde)- o-phenylenediamine Schiff base compound as new capping agent. Pure Ho2O3 nanostructures were prepared by thermal conversion of Ho(OH)(3) nanostructures in air at 600 degrees C for 4 h. The as-obtained nanostructured samples were characterized by field emission scanning electron microscopy (FESEM), energy dispersive X-ray microanalysis (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. Effects of reaction temperature, reaction duration and Schiff base compound as new capping agent on the shape and particle size of the final samples were studied. It was found that the particle size and shape of the samples could be controlled by setting these factors. The photocatalytic behavior of as-obtained Ho2O3 nanostructures was also examined by photodegradation of eriochrome black T dye as water pollutant. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.