Gold nanoparticles supported on Y-zeolite were prepared using the [Au(NH3)(4)](NO3)(3) complex as gold precursor. The differences in the formation of gold nanoparticles in the presence of various co-cations (Na, Cu, Ni or Fe) were discussed in this work. The shift in the plasmon peak observed in the UV-vis spectra for different sample compositions was linked with variation in Au nanoparticle size, as well as changes in the sample chemical composition under thermal treatment. Theoretical spectra for Au nanoparticles supported on modified zeolites were obtained applying an average field model. Qualitative comparison of the data with the theoretical spectra yields insight into the role of distinct co-cations in the system. (C) 2014 Elsevier B.V. All rights reserved.