A novel electrochemical modification method of carbon electrodes with redox active amines is proposed for mediated electron transfer between enzymes and electrodes. Histamine-coordinated Os complex was synthesized as a model redox amine. The electro-oxidation of the complex generated a stable covalent linkage between the nitrogen atom of the amino group and the carbon atom of the electrode surface. The covalent-linked Os complex on the electrode showed a good redox response and a high activity as an electron-transfer mediator between the electrode and a model enzyme: PQQ-dependant water-soluble glucose dehydrogenase.