During the last ten years, the characterization of chemically modified zeolites by electrochemistry has been widely described in the literature. However, the charge transfer mechanism is still not thoroughly understood. There are currently two opposite points of view concerning a hypothetical intrazeolite electron transfer mechanism. In this paper, we review several of the most representative electrochemical studies of encapsulated complexes in the zeolite Y, and we present our experimental results and theoretical hypotheses on the charge transfer mechanism. The second part of this paper deals with the recent interest of electrochemists for the characterization of chemically modified molecular sieves such as MeAPO-5. Identically, we discuss our results and compare them with similar studies found in the literature to reveal the location of electroactive species.