Dielectric and optical properties of 45 P2O5-34 ZnO-(20 −x)Na2O-1 Al2O3-xCuO glasses (0 ≤ x ≤ 5) were investigated. The frequency and composition dependencies of the dielectric parameters were analysed and discussed. The values of real part of dielectric constant (RPDC) lie between 748 to 1169 for RPDCMax, and 654 to 1031 for RPDCMin. The range of values of imaginary part of dielectric constant (IPDC) extends from 39.4 to 57.5 for IPDCMax and from 27.3 to 40.1 for IPDCMin. It was observed that each of these parameters begins to decrease with increasing CuO content, but further addition of CuO causes their rise. Thus, small amount of CuO causes a decrease in both RPDC and IPDC until CuO content reaches 2 mol%, thereafter, they nearly return to their original values at 5 mol% of CuO. Similar behaviour was observed for AC conductivity. Transmittances of the investigated glasses were also measured and used to estimate their optical absorption coefficients and optical band gaps. The optical energy gap is ∼4 eV for the samples with up to 4 mol% CuO, while it is somewhat higher (∼5 eV) for the glass with 5 mol% CuO.