Cubic MnSe2 and octahedral alpha-MnSe microcrystals were successfully synthesized through a convenient hydrothermal method with N2H4 center dot H2O as a reductant and SeO2 and MnCl2 as precursors. The crystalline structure, morphology, and chemical composition of the resulting samples were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectrometer (EDS), and the results indicated that the cubic MnSe2 has an edge size ranging from 5 to 10 pm and the surfaces of these cubes have layer desquamation phenomenon: the alpha-MnSe has an average size of about 10 mu m and the most of these microcrystals are in octahedral shapes. It was also found that the phases and morphologies of the manganese selenides can be controlled by changing the content of N2H4 center dot H2O, reaction temperature, and reaction time. The potential formation mechanism of MnSe2 and a-MnSe was discussed. (C) 2009 Elsevier B.V. All rights reserved.