The temperature- (80–450 K) and frequency- (50−10 4 Hz) dependent dielectric constant, ϵ′, and loss, ϵ″, for Li-doped Bi 4Sr 3Ca 3− z Li z Cu 4O x ( z = 0.0, 0.1, 0.5 and 1.0) glasses, which become high T c superconducting oxides in their crystalline phases, have been measured. Unlike many other semiconducting transition metal oxide glasses, the temperature variations of ϵ′ and ϵ″ of the Li-doped glasses do not have a peak within the frequency range of the investigations. However, the imaginary ( M″) parts of the dielectric modulus, M ∗ , have peaks indicating Debye-type dielectric relaxation behaviour with a distribution of relaxation times. The relaxation behaviour is thermally activated.