For the first time, Ho2O3 nanostructures have been successfully produced through a facile sonochemical way. In this way, diethylenetriamine (dien) as a new precipitator and holmium nitrate were employed to fabricate Ho2O3 products. To optimize the grain size, morphology and photocatalytic efficiency of Ho2O3 samples, the kind of capping agents has been changed. The formed Ho2O3 products have been characterized by means of FT-IR, TEM, EDX, XRD, FESEM and DRS. It was observed that the grain size, morphology and photocatalytic efficiency of the sonochemically produced Ho2O3 were largely dependent on the kind of capping agent. The photocatalytic behaviors of Ho2O3 nano and bulk structures have been compared through decomposition of erythrosine contaminant under ultraviolet irradiation. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.