A direct route has been developed to synthesize nanocrystalline transition-metal selenides via a mild solvothermal process based on the reactions between Se and metal halides MCln (M = Ni, Co, Pb, Sn, Bi) in ethylenediamine at 80-160 degrees C. X-ray diffraction (XRD), transmission electron spectroscopy (TEM), and X-ray photoelectron spectroscopy (XPS) characterized the products as being thin-plate NiSe2, CoSe, PbSe, Bi2Se3, and SnSe nanocrystallites. The formation mechanism was studied.