The copper(II)-phenolate oxygen interaction in several mixed-ligand complexes of copper(II) containing a 2,2′,2″-terpyridyl and a phenolate has been studied by i.r., electronic, e.p.r. spectroscopies and conductometric and polarographic measurements. Electronic spectral results demonstrate the dependence of such interaction on the nature of the phenol as well as the solvent. Partial dissociation of the phenolate from the complex was detected in methanol at low concentrations (≤1×10−4M). In dimethyl sulphoxide the complexes remain intact. The X-band e.p.r. spectral data obtained at ambient temperature and at 77 K are consistent with the results from the electronic spectral and conductometric study.