The effect of substituting Na+ counterion of Aerosol-OT [sodium bis(2 ethylhexyl) sulfosuccinate] with doubly charged counterion Cu2+ has been studied for the Cu(AOT)(2)/H2O/CCl4 system by infrared and dielectric spectroscopy as a function of surfactant concentration and water content. A relaxation phenomenon has been observed whose behavior depends strongly on the degree of surfactant hydration W(W = water-to-surfactant molar ratio). The hydration of Cu(AOT)2 reverse micelles has also been investigated by means of IR spectroscopy. IR spectra of surfactant-entrapped water show a notable complexity, which could be ascribed to strong interaction between the Cu2+ counterion and water inside the micellar core. The results of IR and dielectric spectroscopy studies have been compared and discussed with those previously obtained for the corresponding NaAOT and Ca(AOT)(2) reverse micelles.