The aim of my studies was to determine the exact coordination modes of copper(II) complexes of ProHisLeu tripeptide and investigate the electrochemical characteristics of those complexes. In this work, the combined application of potentiometric, spectroscopic, and electrochemical measurements on the Cu(II) complexes of ProHisLeu was studied, in samples containing metal ions and ligand in 1:1 and 1:5 ratios. The ligand deprotonation constants were calculated using SUPERQUAD software. The exact coordination modes and electrochemical characteristics of copper(II) complexes of ProHisLeu tripeptide were determined.