Defect fluorite, Bi-doped Pr6O11, was studied as a cathode and it was found that Bi doped Pr6O11 exhibits high surface activity for the cathode reaction, and an all-fluorite concept SOFCs is successfully demonstrated by using Ce0.6Mn0.3Fe0.1O2 for anode. Diffusivity and surface activity in Bi doped Pr6O11 was further studied with O-18(2)-16O(2) gas phase exchange and a surface activity was competitively high with that of La0.6Sr0.4Fe0.8Co0.2O3 (LSFC), and this high surface activity is a result of the large oxygen vacancy in Pr6O11. The power generation property of the cell was also examined by using C3H8 and the power density of 0.4 W/cm(2) was exhibited when dry C3H8 was directly used for a fuel because of decreased IR loss. (C) 2014 Elsevier B.V. All rights reserved.