Semiconductor photocatalysis has proved to be an efficient method for decolorization and degradation of pollutants. In this study, a common semiconductor, CuO, as doped with synthetic zeolite NaX via wet impregnation of parent zeolite with Cu(NO3)(2) aqueous solution was prepared. The potential of the obtained photocatalyst in decolorization of methylene blue (MB) dye under sunlight irradiation was studied. Characterization of parent zeolite NaX and prepared samples were studied using X-ray powder diffraction (XRD) patterns, infrared spectroscopy (FT-IR) spectra, diffuse reflectance spectroscopy (DRS), thermo analytical techniques (TG/DTG and DSC), SEM and BET methods. The active component value (CuO) on parent zeolite was also determined by atomic absorption spectroscopy (AAS) method on digested catalyst. The influence of experimental parameters on the dye photodecolorization process was studied and it was observed that photoreactivity of photocatalyst (CuO/X) varied with the amount of catalyst, initial dye concentration, pH of the dye solution, temperature, and active component value (CuO) loading. The role of zeolite NaX as a support was also investigated on decolorization rate. The optimal experimental conditions were determined as follow: catalyst amount; 1.0 g L-1, concentration of the dye solution; 0.03 mM, pH of solution; 11, and active component value; 88 mg CuO per gram of the catalyst. Under these optimum conditions, the obtained decolorization efficiency for MB dye was 94%. The reusability of the intended catalyst was also investigated. (C) 2010 Elsevier By. All rights reserved.