The electrolysis of pyrazoline-5-ones and isatins in alcohols in an undivided cell results in the fast (16 min.) and efficient formation of the substituted 3-hydroxy-3-(3-hydroxy-5-methyl-1H-pyrazol-4-yl) indol-2-ones in 77-95% substance yields and 1540-1900% current efficiency. This novel electrocatalytic chain process opens a fast efficient and convenient way to functionalized 3-hydroxy-3-( 3-hydroxy-5-methyl-1H-pyrazol-4-yl)indol-2-ones- the promising compounds for the different biomedical applications. Thus, the simple electrocatalytic system can produce in aprotic solvent in an undivided cell, under mild conditions the electrochemically induced aldol reaction of isatins and pyrazoline-5-ones. (C) 2014 The Electrochemical Society. All rights reserved.