Abstract. The present work deals with the composite system (CuI)x(Ag2OTeO2)100x, where x=30, 35, 40, 45, 50, 55, 60, 65, 70 and 75mol%, respectively, synthesized by a solid-state reaction route. Powder specimens were analysed using differential scanning calorimetry, X-ray diffraction and Fourier transform infrared techniques. These studies have revealed the formation of Cu3TeO6, AgI and/or other phases. The ambient temperature electrical conductivities obtained for the samples using a complex impedance method were found to lie in the range 106104Scm1, with low activation energies, thus indicating their superionic nature. The typical composition 35CuI32.5Ag2O32.5TeO2 was identified as the best conducting one, having an electrical conductivity of 6104Scm1 at 296K and an activation energy of 0.23eV. Ion transport number measurements carried out using Wagner's polarization technique as well as by an electromotive force method suggested that silver ions were responsible for the observed transport features of the composite system.