The strategy of paired electrochemical synthesis of organic compounds in undivided cell process in which the reaction product at the anode and the reaction product at the cathode are simultaneously separated was performed. In order to evaluate the feasibility of the process the electrochemical oxidation of fructose to gluconic acid and the reduction of fructose to sorbitol and mannitol were paired in an electrocatalytic membrane reactor. However, only the results obtained on the electrochemical reduction are described in this work as it required catalysis to be performed successfully. The reactor is made with two coaxial tubes of membrane support. Some parameters which modify the electrocatalytic activity of the electrode are studied. (C) 2000 Elsevier Science B.V. All rights reserved.