Abstract The ac-conductivity and dielectric response of new composites based on zinc-phosphate glass with composition 45 mol%ZnO–55 mol%P 2 O 5 , filled with metallic powder of nickel (ZP/Ni) were investigated by impedance spectroscopy in the frequency range from 100 Hz to 1 MHz at room temperature. A high percolating jump of seven times has been observed in the conductivity behavior from low volume fraction of filler to the higher fractions, indicating an insulator – semiconductor phase transition. The measured conductivity at higher filler volume fraction is about 10 −1 S/cm and is frequency independent, while, the obtained conductivity for low filler volume fraction is around 10 −8 S/cm and is frequency dependent. Moreover, the elaborated composites are characterized by high dielectric constants in the range of 10 5 for conductive composites at low frequencies (100 Hz). In addition, the distribution of the relaxation processes was also evaluated. The Debye, Cole-Cole, Davidson–Cole and Havriliak–Negami models in electric modulus formalism were used to model the observed relaxation phenomena in ZP/Ni composites. The observed relaxation phenomena are fairly simulated by Davidson–Cole model, and an account of the interpretation of results is given.