PrNO4-based oxide was studied as a new mixed electronic and oxide ionic conductor for the oxygen permeation membrane. It was found that Pr2NiO4 doped with Cu and Fe for Ni site exhibits the relatively high oxygen permeation rate. Doping second cation to Ni site is effective for improving the oxygen permeation rate and the trivalent cation seems to be effective for increasing the oxygen permeation rate. Among the examined cation, the highest oxygen permeation rate was obtained by doping 5 mol% Fe. The oxygen permeation rate was also significantly affected by the surface catalyst and the highest oxygen permeation rate of 80 mu mol(.)min(-1.)cm(-2) at 1273 K was achieved by using La0.1Sr0.9Co0.9Fe0.1O3 for the surface catalyst. Since the electrical conductivity slightly decreased with decreasing P-O2, and it dropped significantly at P-O2 = 10(-19) atm, chemical stability of Pr2NiO4-based oxide seems to be reasonably high. Application of this new mixed conductor for the oxygen permeation membrane under the CH4 partial oxidation was also studied and it was confirmed that the oxygen permeation rate much improved under the CH4 oxidation condition and this Pr2NiO4 can be used for the oxygen permeation membrane for the CH4 partial oxidation. (c) 2006 Elsevier B.V. All rights reserved.