Fast ionic conductors XLiTiO2-YB2O3 with X:Y = 90:10 and 80:20 are prepared by the solid-state reaction method and subjected to ac conductivity measurements with silver electrodes in the frequency range 42 Hz to 5 MHz. The ac conductivity values are 6.47 x 10(-5) and 2.2 x 10(-7) Omega(-1) cm(-1), respectively. The ion hopping rate and charge carrier concentration are calculated by fitting the conductance spectra to the power law equation, using Almond and West formalisms. The charge carrier concentration is in the order of 10(25) and is independent of temperature, which supports the strong electrolyte model. The conductivity relaxation time is calculated from the peak frequency of the modulus spectra. The effect of B2O3 substitution is discussed. (C) 2003 Elsevier Science B.V. All rights reserved.