The electrical properties of the fresnoite BaO-TiO2-SiO2 system were studied over a range of amorphous and crystalline microstructures using as-quenched glass (BTS-gl), partially crystallized glass (BTS-pc, heat treated at 740 degrees C for 100 min) and fully crystallized glass ceramic (BTS-gc, heat treated at 750 degrees C for 180 min). Combination of impedance and moduli plots along with equivalent circuit models were utilized in an attempt to understand the contributions arising from different regions in the glass ceramic, i.e. the glassy matrix, crystalline phase, and crystal-glass interface region. Electrical conductivity of the samples exhibited frequency dispersions at different temperatures suggesting localized motion of ions. The activation energies calculated from dc resistivity-temperature plots (E-dc) and relaxation frequency-temperature plots (E-f) seem to increase as the degree of crystallinity increases suggesting that ionic transport becomes more difficult in crystallized glasses.