An electrolytic reductive cleavage of tosyl group in N-tosyl amino acids was carried out by the use of 2 mol equivalent of NaCl or KCl as an electrolyte to the tosyl amino acids and of lead as a cathode in methanol–water. The procedure was applicable to the cleavage of N-tosyl peptides with preservation of the peptide bond, and with retention of their optical activity. No cleavage of the other protecting