Many binary transition metal sulfides nanocrystallites MS (M = Zn, Cd, Co, Ni) with different morphologies have been successfully prepared in an ethylenediamine solution of metal salts and (NH4)(2)S (or thiourea) using a facile hydrothermal method. The products are characterized by powder X-ray electron diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and the selected area electron diffraction (SAED), respectively. UV-visible optical absorption spectra clearly indicate the presence of quantum size effects in some transition metal sulfides nanocrystallites and the possible mechanism of ethylenediamine-assisted is also briefly discussed. This method may also be extended to controllable synthesis of other metal chalcogenides with different morphologies, such as nanowires, nanorods, and nanodisks, etc. (C) 2004 Elsevier B.V. All rights reserved.