New inorganic–organic hybrid compound was obtained and characterised by powder X-ray diffraction, UV–vis spectroscopy. This nanocomposite material is composed of ZnSe layers and m-xylylenediamine (MXDA) molecules which link inorganic layers. This class of compounds exhibits quantum confinement effect: the optical absorption experiments show that the absorption edge of the title compound exhibits large blue shift.The crystal structure model of ZnSe(MXDA) 1/2 has been found using direct methods and global optimisation techniques, and refined by the Rietveld method. The title compound crystallises in the orthorhombic crystal system, space group Ccm2 1 (No. 36), Z=8. Crystal data: a=6.7346(8)Å, b=24.9804(2)Å, c=6.4428(6)Å, and V=1083.9(2)Å 3 .