Synthesis of polyacrylonitrile (PAN)-organoclay nanocomposite was studied through grafting of PAN onto organophilic kaolinite. The organophilic kaolinite was prepared by treatment of kaolinite with different ratios of hexadecylethyldimethylammonium (HDEDMA) to kaolinite. The chemical grafting polymerization of acrylonitrile (AN) onto organophilic kaolinite was performed. The synthesized polymer-organoclay nanocomposite was studied for simultaneous adsorption of Cr(VI) and methylene blue dye (MB) from aqueous solutions. The results of Cr(VI) or the dye adsorption revealed that the adsorbed amounts increased with increasing HDETMA concentration. The removal percentage of Cr(VI) reached more than 98 % if individually studied, while 96 % was obtained when competing with dye. Also the adsorption of Cr(VI) was potentially influenced by its concentration in solution. The isothermal studies were performed using Langmuir and Freundlich models. The maximum calculated adsorption capacity was found to be 127 mg g-1 and 68 mg g-1 for Cr(VI) and methylene blue, respectively for individual adsorption, while in simultaneous adsorption their adsorption capacity was not affected by the other.