The preparation of the (N,N'-diarylacetamidine)rhodium(III) complex in the cavities of zeolite Y is reported. The guest rhodium(III) complex was entrapped in the supercages of zeolite Y as a host by a two-step process in the liquid phase: (I) inclusion of rhodium(III) by ion-exchange in the structure and (II) introduction of N,N'-diarylacetamidine ligand followed by assembly of the complex inside the void space of the zeolite. The neat complex has also been prepared and characterized. The appropriate process selected for the in situ complex synthesis involved using an N,N'-diarylacetamidine ligand : rhodium(III) molar ratio of 4 : 1. Spectroscopic studies (Fourier transform infrared spectroscopy), chemical analyses, surface (X-ray photoelectron spectroscopy, scanning electron microscopy and X-ray diffraction) and cyclic voltammetric studies were used to characterize the new host-guest materials. Analysis of the data of the neat and encapsulated complex show that the coordination of the rhodium(III) ion (as a guest in the host structure) by the nitrogen atoms of the N,N'-diarylacetamidine ligand occurred in a 2 : 1 stoichiometry.