The structure and electric conductivity of glasses in the system RNO3-Zn(NO3)(2)-KHSO4-P2O5 (R=Na, K) obtained at different temperatures were investigated by IR and impedance spectroscopy Glasses fused at 250-350 degrees C demonstrated an increase of their ionic conductivity in 10(3) times in comparison with the same compositions fused at 550 degrees C. The'influence of the chemical composition on the structure and properties of the obtained glasses was analyzed. It is proposed that the high ionic conductivity of glasses obtained at low temperatures is related to the incorporation of the nitrate ions between long (PO3)(n) chains, similar to the iodide ions; this resulted in a maximal coordination of the local conduction space for the cation associated with a disordered glass network. (c) 2006 Elsevier B.V. All rights reserved.