In a previous study, the feasibility to work in hydro-organic media in electrodialysis (ED) was demonstrated with a good efficiency. In this paper, the possibility to work with one or more compartments filled with organic solutions was proved. The characterization of solvent with Raman spectroscopy allows us to evaluate the diffusion and electro-osmosis flux, in presence of salts in solution. ED in mixed media can be achieved with a low leakage of solvent. A low anion leakage and a high faradic yield were pointed out with this configuration. It suits well to convert salts, which are not soluble in water like fatty acid salts with length carbon chain (as palmitic acid sodium salt). The conversion into acid was achieved with more 94% of purity. In the second part of our study, electro-synthesis assisted by membrane was undertaken. The conversion of palmitoyl chloride to the methyl palmitic ester was carried out in dichloromethane solution. The comparison of the final product with the commercial ester shows a high purity of our synthetic ester. (C) 2004 Elsevier B.V. All rights reserved.