EPR and optical spectra of copper diffusion layers obtained by ion exchange in glasses of composition (mol. %) X Na 2O(20 X)Li 2O10Al 2O 370SiO 2 (where X = 20 X = 13.5) and 20Na 2O10K 2O10Al 2O 360SiO in2 are studied. It is concluded that Cu 2+ enters the glasses. The concentration profile of Cu 2+ ions repeats the concentration distribution of the copper element in diffusion layers. It is assumed that the equilibrium between Cu 2+ ions, Cu 1+ ions and colloids takes place throughout the depth of the diffusion layers. The local environment of Cu 2+ in the diffusion layer proves to be qualitatively similar to that for Cu 2+ ions in bulk glasses. It is shown that the complexes of Cu 2+ ions typical of a given glass composition approach their equilibrium states at T = 550°C for τ d of about 30 min.