A combination of a selective enzymatic oxidation with an unselective electrochemical reduction step was applied for deracemization, stereoinversion and asymmetric synthesis Of L-leucine (starting from racemic leucine, D-leucine or 4-methyl-2-oxovaleric acid) in a batch reactor. D-Amino acid oxidase (D-AAO) from Trigonopsis variabilis was used as enzyme. Reaction conditions for the electrochemical and enzymatic reactions were investigated separately and finally combined to an electroenzymatic synthesis, yielding 3.5 mmol L-1 d(-1) of L-leucine (ee 91%). (C) 2007 Elsevier Ltd. All rights reserved.