ZnS nanoparticles were prepared and deposited on montmorillonite (MMT) in the presence of cetyltri-methylammonium (CTA) UV spectrometry and transmission electron microscopy (TEM) proved the formation of nanoparticles with diameters ranging from 3 nm to 5 nm Selected area electron diffraction (SAED) patterns revealed the presence of romboedric ZnS The band gap energy of nanosize ZnS was estimated at 3 89 +/- 0 03 eV Photoluminescence spectra exhibited a strong emission band between 300 nm and 600 nm explained by the vacant ZnS nanostructure The prepared ZnS-montmorillonite nanocomposite (ZnS-MMT) was used for the photocatalytic reduction of CO2 providing a considerably high efficiency that exceeded 5-6 fold the results of commercial TiO2 Degussa P25 The main reaction products were hydrogen and methane Methanol and carbon oxide were also observed in about 7 fold lower amounts The stability of ZnS against oxidation was confirmed by the determination of sulphate using capillary isotachophoresis (C) 2010 Elsevier Inc All rights reserved