An application of membrane reactors in electrochemical synthesis is presented. The membrane separations utilise an appropriate solvent extraction process either as a pertraction, an emulsion membrane filtration or a supported liquid membrane. The electrosynthesis considered is an indirect process involving the oxidation of an organic species using an appropriate active metal ion species generated anodically. A model of this membrane reactor system is presented involving interphase mass transport across the membrane, in the form of a hollow fibre, from the organic reagent to the aqueous electrolyte. The model provides the basis for simulation of the process operation and thus a cost estimation of the process. Preliminary costing of the use of membrane reactors shows that significant benefits can result with certain systems.