The glass forming ranges in the TeO2-AgO0.5 and TeO2-AgO0.5-AgI systems have been assessed for two cooling rates; results based on heat capacity and electrical conductivity measurements as well as derived from infrared spectroscopy are presented. The ternary glasses are excellent conductors due to the presence of Ag+ ions mainly supplied by AgI. The decrease in ΔCP with increasing AgI-content suggests the presence of AgI microdomains which are finely distributed and do not contribute to the configurational heat capacity change. Fast motion of Ag+ ions (low activation energy) occurs in the glassy matrix which shows slow structural relaxation (high activation barrier).