Nanoparticles of electrogenerated zinc-supported HY zeolite (EGZnO/HY) catalyst were prepared by a simple electrochemical method. The interaction between zinc species and HY support during the electrolysis was found to affect the EGZnO/HY structure. In addition to the formation of EGZnO nanoparticles (<30 nm in size) that distributed on the surface of HY support, an isomorphous substitution of Al with Zn also occurred in the aluminosilicate framework to result in a Si-O-Zn bonds. The photoactivity of EGZnO/HY was tested on the decolorization of methylene blue (MB). An amount of 0.375 g L-1 of 1 wt% EGZnO/HY was found to be the optimum dosage for 10 mg L-1 MB, which resulted in 80% of maximum decolorization after 6 h of contact time at pH 3 under fluorescent light (420 nm). Increasing the EGZnO loading led to additional formation of Si-O-Zn bonds and lessened the number of EGZnO nanoparticles, which then reduced the photodecolorization percentage of MB. The photocatalytic reaction was follows the first-order Langmuir-Hinshelwood model, and gives partially mineralization. The photocatalyst was still stable after five cycling runs with no Zn leaching. (C) 2013 Elsevier B.V. All rights reserved.