Glasses containing nanometer sized particles of CuInS 2 (10 to 70 nm) were fabricated and characterized. The lattice structure of nanoparticles determined by X-ray diffraction is different from bulk CuInS 2 that can provide features of optical properties of the glasses. This change of lattice is proposed as a possible reason for the low-energy shift of the fundamental absorption edge observed for nanoparticles as compared with bulk CuInS 2 .