The purpose of this study is the use of boron-doped diamond （BDD） electrodes for the electrochemical analysis of N,N,N',N'-Tetrakis （2-hydroxypropyl） ethylenediamine （Quadrol） as an additive in copper pyrophosphate plating baths. Actually, BDD is a quite new electrode material. Non-doped diamond shows electrical insulating properties, but its conductivity changes according to the doping concentration of boron from semiconductive, metallic conductive, to superconductivity. Moreover, BDD has unique electrochemical properties such as a wide potential window, low background current, and chemical stability. Metallic conductive BDD electrodes have been used for the electrochemical analysis of Quadrol additives. Earlier, we reported that Quadrol additives included in copper pyrophosphate plating baths had the effect of improving the appearance of thus-plated film, even under high current density. Cyclic voltammogram （CV） measurements for Quadrol in a copper pyrophosphate plating bath using BDD or Glassy carbon （GC） electrodes suggest that the BDD electrode showed anodic current, which was thought to be attributed to the oxidation of Quadrol at ca. 1.65 Vvs. SCE. Comparison with GC electrodes has clarified differences in the oxidation mechanism of Quadrol on each electrode. Furthermore, LSV measurements for BDD electrodes suggest the possibility of quantification of Quadrol in the bath.