KTa0.1Nb0.9O3 (KTN) particles with an orthorhombic perovskite structure have been synthesized via a high temperature mixing method (HTMM) under hydrothermal conditions. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high-resolution transmission electron microcopy (HRTEM). The influence of alkaline concentration and solvent composition on the phase structure and morphology of the obtained powders was investigated. The results show that the well-crystallized KTN powders with sizes of 200-500 nm are successfully prepared at temperatures as low as 240 degrees C when the KOH concentration is 2.0 M and the isopropanol/water (I/W) volume ratio equals to 100/0. (C) 2011 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.