Part of our research effort aims to design novel, enzyme-based, high surface area materials capable of efficiently transferring electrons between chemicals and electrodes for application as biosensors and biofuel cells. These bioelectrochemical reactions are enabled by designing novel, efficient, mediated electron transfer processes between selected enzymes and electrode materials. To advance our understanding of integrating immobilisation and function (electron transfer efficiency) we have commenced synthesis of a library of osmium/ruthenium-based redox mediator complexes possessing a range of redox potentials, with each complex in the library amenable to simple immobilisation chemistry. This immobilisation can be achieved either through ligand substitution with a suitable polymer support or through covalent coupling of designed functional groups of the complex to supports. In addition to designing immobilisation for the mediators, we have also commenced research on anchoring redox systems, and enzymes, onto electrode supports, using gold-thiol adsorption and reductive coupling of diazonium salts to carbon to provide functionalised electrode surfaces. This anchoring chemistry can improve the stability of the enzyme/mediator layer and offer improved mediated bioelectrochemical systems for application as biosensors and biofuel cells.