By combination of supercritical drying route and coprecipitation synthesis method, ultrafine Ce0.8Gd0.2O1.9 (GDC20) nano-powders are successfully prepared using (NH4)(2)CO3 as the precipitant. The as-synthesized powder has a specific surface area of 113.4 m(2) g(-1) and an average crystalline size of similar to 6 nm after calcination at 400 degrees C, together with other favorable properties like high dispersibility, weak agglomeration and remarkable flowability. The powder shows high sintering activity, where the relative density reaches similar to 99.9% with an average grain size of similar to 100 nm after sintered at 900 degrees C for 4 h. Low temperature sintering not only suppresses grain growth but also improves electrical performance of the electrolyte. The sample sintered at 900 degrees C exhibits high electrical conductivity of 5.39 S m(-1) at 700 degrees C, which is superior to most of the reported ceria-based electrolyte. (C) 2015 Elsevier Ltd. All rights reserved.