In this paper, inorganic-organic hybrid semiconductor (ZnSe)(N2H4)(x)(C5H5N)(y) nanosheets as well as (ZnSe)(C5H5N)(y) nanoparticles were first synthesized by a solvothermal method in a ternary solution and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra, ultraviolet-visible (UV-vis) absorption spectra, thermogravimetric analysis (TGA), differential scanning calorimeter (DSC) and photoluminescence (PL) spectra. The results indicated that the morphology and composition of the products were largely influenced by the reaction temperature and the volume ratio of water. When the reaction temperature and the water content were lower, (ZnSe)(N2H4)(x)(C5H5N)(y) nanosheets were formed. As the reaction temperature or the content of water was high enough, (ZnSe)(C5H5N)(y) nanoparticles were formed. Pure hexagonal wurtzite ZnSe nanosheets or zinc blende ZnSe nanoparticles were obtained by extracting the corresponding hybrids. The bandgap absorption of ZnSe nanocrystals blue shifted in comparison with the bulk. The photoluminescent intensity of (ZnSe)(N2H4)x(C5H5N)(y) nanosheets was much stronger than that of (ZnSe)(C5H5N)(y) nanoparticles. (C) 2008 Elsevier Ltd. All rights reserved.