The electrolysis of isatins and cyclic 1,3-ketoesters in acetone in an undivived cell results in the formation of the previously unknown 3-substituted-3-hydroxyindol-2-ones in 80-95% yields and 800-950% current efficiency. Thus, this simple electrocatalytic system can produce in aprotic solvent in an undivided cell, under mild conditions the new electrochemically induced aldol reaction of isatins and cyclic 1,3-ketoesters with the formation of 3-substituted-3-hydroxyindol-2-ones - promising synthons for different biomedically active compounds. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.021211jes] All rights reserved.