MnSe2/Se nanocomposites have been successfully synthesized through a hydrothermal process by using SeCl4 and MnCl2 center dot 4H(2)O as starting materials, in presence of polyethylene glycol 600 (PEG 600) and hydrazine (N2H4 center dot H2O) as surfactant and reductant, respectively. It was found that hydrazine concentration has significant effect on morphology and phase of the final products. The possible formation mechanism of different morphologies was briefly proposed. This work has provided a general, simple, and effective method to control the composition, phase structure and morphology of metal selenides in aqueous solution, which will be important for inorganic synthesis methodology and further applications of selenides. (C) 2013 Elsevier Ltd. All rights reserved.