The Ag2O-TiO2-SiO2 glasses were prepared by Ag+/Na+ ion-exchange method from Na2O-TiO2-SiO2 glasses at 380450 degreesC below their glass transition temperatures (T-g), and their electrical conductivities were investigated as functions of TiO2 content and the ion-exchange ratio (Ag/(Ag+Na)). In a series of glasses 20R(2)O.xTiO(2).(80-x)SiO2 with x=10, 20, 30 and 40 in mol%, the electrical conductivities at 200 degreesC of the fully ion-exchanged glasses of R=Ag were in the order of 10(-5) or 10(-4) S cm(-1) and were 1 or 2 orders of magnitude higher than those of the initial glasses of R=Na. The glass of x=30 exhibited the highest increase of conductivity from 3.8 X 10(-7) to 1.3 x 10(-4) S cm(-1) at 200 degreesC by Ag+/Na+ ion exchange among them. When the ion-exchange ratio was changed in 20R(2)O.30TiO(2).50SiO(2) system, the electrical conductivity at 200 degreesC exhibited a minimum value of 7.6 x 10(-8) S cm(-1) around Ag/(Ag+Na)=0.3 and increased steeply in the region of Ag/(Ag+Na)=0.5-1.0. When the ion-exchange temperature was changed from 450 to 400 degreesC, the conductivity of the ion-exchanged glass of x=30 decreased. The infrared spectroscopy measurement revealed that the ion-exchange temperature of 450 degreesC induced a structural change in the glass of x=30. The T-g of the fully ion-exchanged glass of x=30 was 498 degreesC. It was suggested that the incorporated silver ions changed the average coordination number of titanium ions to form higher ion-conducting pathway and resulted in high conductivity in the titanosilicate glasses. (C) 2003 Elsevier Science B.V. All rights reserved.