The Lu2+xTi2-xO7-x/2 (x=0; 0.052; 0.096; 0.286; 0.44; 0.63; 33.3-49 mol% Lu2O3) nanoceramics with partly disordered pyrochlore-type structure are prepared by sintering freeze-dried powders obtained by a co-precipitation technique with 1600 degrees C annealing. Similar to pyrochlorelike compositions in the zirconate system, some of the new titanates are good oxide-ion conductors in air. The new solid-state electrolytes have oxide-ion conductivity in the interval of 1.0 x 10(-3) - 2.5 x 10(-3) S/cm at 740 degrees C in air. This value of conductivity is comparable with that Of ZrO2/ Y2O3 ceramics. The conductivity of Lu2+xTi2-xO7-x/2 depends on the chemical composition. The highest ionic conductivity is exhibited by nearly stoichiometric Lu2+xTi2-xO7-x/2 (x=0.096; 35.5 mol% Lu2O3) material containing similar to 4.8 at.% Lu-Ti anti-site defects. (c) 2006 Elsevier B.V. All rights reserved.