Tailoring the interfacial region of composite modified electrodes has been a topic of discussion for over a decade. This research examines the electrochemical effects of the formation of unique interfacial regions in surface-modified glass microsphere/polyvinylpyridine composite modified electrodes and surface-modified glass microsphere/polystyrene sulfonate composite modified electrodes. The surfaces of the glass microspheres are modified with different organic functional groups by binding organosilanes to the surfaces of the glass microspheres through a siloxane linkage. This research showed that surface-modified glass microspheres can alter the electrochemical flux through both surface-modified glass microsphere/polyvinylpyridine, composites and surface-modified glass microsphere/polystyrene sulfonate composites of hydroquinone, Ru(bpy)(3)(2+), and ferricyanide. It was also shown that the polymer itself plays a crucial role in the formation and the properties of the interfacial region. The interfacial region was imaged using fluorescence microscopy, and the microscopy showed that a highly concentrating interfacial region is formed for all of the surface-modified glass microsphere/polymer composites studied regardless of whether there is an electrochemical effect. Further studies with smaller particles are necessary to obtain a large enough interfacial region to be useful for sensor development.