Nano-sized nickel selenide powders have been successfully synthesized via an improved hydrothermal route based on the reaction between NiCl2 center dot 6H2O, SeCl4 and hydrazine (N2H4 center dot H2O) in water, in present of cetyltrimethyl ammonium bromide (CTAB) as surfactant, at various conditions. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray energy dispersive spectroscopy analysis. Effects of temperature, reaction time and reductant agent on the morphology, the particle sizes and the phase of the final products have been investigated. It was found that the phase and morphology of the products could be greatly influenced by these parameters. The synthesis procedure is simple and uses less toxic reagents than the previously reported methods. Photoluminescence (PL) was used to study the optical properties of NiSe samples. (C) 2011 Elsevier B.V. All rights reserved.