In many fields such as fine chemistry and pharmacy, biotechnology is increasingly being used to produce natural-like molecules of great interest. The main method remains fermentation which results in complex mixtures in which there is only a very small amount of the required compound. Numerous downstream separation steps are necessary, which are expensive and generate large amounts of polluting wastes such as solvents, resins or salts. Using free enzymes extracted from microorganisms would avoid most of these separations and wastes. Oxidoreductases catalyse a lot of electron transfer reactions involved in many economically interesting syntheses, but electron extraction or feed is still a critical stage in developing free enzyme processes with them. The use of an electrochemical reactor to ensure electrical extraction or feed would provide a good step towards cleaner processes because the highest selectivity would be ensured without any by-products being generated. The first purpose of this paper is to show the broad application held of oxidoreductases in which electrochemistry could be introduced with some benefit. A concise analysis of the first electroenzymatic reactor design shows that in order to develop such economically efficient reactors, the enzymes must be confined in the strict vicinity of the electrode surface. Consequently, the experimental part is devoted to the development of an electrode/enzyme interface specificially adapted to synthesis processes. Electropolymerisation of pyrrole on a platinum electrode was used to entrap successively glucose oxidase for gluconic acid production, and hydrogenase for NADH regeneration. Emphasis was placed on increasing the mass transfer rates in the him and the amount of enzyme retained.