A series of nanocrystalline MxZn1-xFe2O4 (M = Ni, Mn and Co; x = 0.40-0.60) powders have been successfully prepared via hydrothermal process and characterized by XRD, TEM and IR techniques. The effects of reaction temperature and the initial pH value of the starting suspension solution on the particulate properties such as the particle size and morphology are discussed. IR spectra indicate that there are no hydroxyl in as-prepared NixZn1-xFe2O4 and CoxZn1-xFe2O4 powders, while there are obvious hydroxyl adsorption on the IR spectrum of MnxZn1-xFe2O4 powder. (C) 2002 Elsevier Science Ltd. All rights reserved.