Ag-108m tracer diffusion, ac impedance measurements and Wagner dc polarization experiments show that xAgI(center dot)(1 - x)As2Te3 glasses (0 <= x <= 0.8) prepared either by traditional thermal synthesis in vacuum or by mechanical milling exhibit drastic changes in electronic and ionic conductivity as a function of silver iodide content x. The ionic transport increases monotonically by 9 orders of magnitude while the electronic conductivity decreases by a factor of 10(4) with increasing x. The x < 0.5 glasses are essentially amorphous semiconductors with the silver ion transport number between 10(-8) <= t(Ag)(+) < 0.5. The AgI-rich compositions, 0.6 <= x <= 0.8, belong to superionic glasses with the residual electronic conductivity of n-type, 10(-5) <= t(n) <= 0.01. (C) 2013 Elsevier B.V. All rights reserved.