Electrical communication between the flavin adenine dinucleotide redox centers of glucose oxidase and a conventional electrode has been achieved using two electron transfer relay systems based on siloxane-ethylene oxide copolymers containing covalently attached ferrocene moieties. The results from stationary potential experiments show that carbon paste electrodes modified with these redox polymers and glucose oxidase respond rapidly to addition of glucose, with larger steady-state response currents than those measured in previous studies of glucose sensors based on ferrocene-modified siloxane polymers. The results also indicate that the mediating ability of the polymers is dependent upon the length of the ethylene oxide side chain onto which the ferrocene molecules are attached.