The infrared spectra of [Cu (glutamate)·(H₂O)]_n·(H₂O)_n, [Zn (glutamate)·(H₂O)]_n·(H₂O)_n and their isotopic complexes containing metal and hydrogen isotopes have been measured in the region between 4000 and 200 cm^-1. The isotope shifts on ⁶³Cu and ⁶⁵Cu substitution have been observed for bands at 404, 352 and 279 cm^-1 of the Cu complex. Bands at 300, 245 and 227 cm^-1 of the Zn complex are apparently sensitive to ⁶⁴Zn and ⁶⁸Zn substitution. The frequency shifts on N, O-deuteration indicated that a Cu-OOC stretching vibration is localized for the Cu complex whereas Zn-OOC stretching vibrations couple with Zn-NH₂ and/or Zn-OH₂ stretching vibrations.