Chronopotentiometric stripping (CPS) peak H in proteins is due to the catalytic hydrogen evolution reaction (CHER) involving amino acid residues. This peak is sensitive to changes in protein structures, representing a new tool in protein research. Here we show on the ground of studies of CPS behavior of four angiotensin peptides that at neutral pH arginine plays a critical role in CHER at Hg electrode, while participation of histidine residues in this reaction is very weak. At carbon electrode tyrosine residues produce an oxidation peak close to 0.7V but the presence of histidine in angiotensins is not manifested by any oxidation peak.