To explore their possible application as solid electrolytes in Solid Oxide Fuel Cells (SOFC), this contribution presents the synthesis, characterization and electrical properties of Ln(4)Zr(3)O(12) (Ln = Y, Ho, Er and Yb) zirconates. All samples were obtained by mechanical milling and their electrical properties were analyzed as a function of frequency and temperature, by using impedance spectroscopy. Our results show that defective fluorite-type zirconates might be successfully obtained after milling stoichiometric mixtures of the corresponding oxides, for 30-40 h in a planetary mill. Such structural form persists even after firing the as-prepared Y, Ho and Er zirconates, at very high temperatures (1500 degrees C); whereas, Yb4Zr3O12 shows a transition to a rhombohedral delta-phase on firing. Ionic conductivity (sigma) values obtained for all compositions at 700 degrees C (including fluorites and delta-phase), are comparable to those reported for similar ionic conductors, and within the 10(.-3.82) to 10(-613) S cm(-1) range. Higher sigma values were obtained for those zirconates preserving the disordered fluorite-type structure after firing. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.