NOVELTY - Sintering air electrode of a temporarily sealed metal-supported solid oxide cell involves: (a) protecting porous metal of the cell through covering the porous metal with a non-porous metal sheet; and (b) heating the un-sintered air electrode layer as applied to the cell to a temperature higher than 700 degrees C in the presence of a gas with a non-reducing composition while preventing exposure of the enclosed active area of the fuel electrode to the same gas by action of the seal and without any additional flow of gases containing hydrogen.    USE - The processes are useful for sintering air electrode of temporarily sealed metal-supported solid oxide cell; and for preparing solid oxide cell stack (all claimed).    ADVANTAGE - The improved process greatly lowers the risk of mechanical damage to the electrolyte of the cell; permits stack conditioning to be completed at a lower temperature (e.g. the operation temperature); permits a high compression force due to this lower conditioning temperature, thus decreasing the amount of harmful gas leakage; creates a much more uniform sintering of the air electrode, so that certain portions of the cell area will not be better sintered others; and permits inspection of the cells prior to stacking, so that any defective units may be rejected, where a later stack failure can be avoided. Cell is also provided which is relatively cheap and at the same time more robust than previously known cells.    DETAILED DESCRIPTION - Sintering air electrode of a temporarily sealed metal-supported solid oxide cell involves: (a) protecting porous metal of the cell through covering the porous metal with a non-porous metal sheet, thus creating an enclosure, which is done by attaching the fuel electrode of a cell not having a sintered air electrode towards a non-porous metal object, thus forming a seal located within the perimeter of the cell while not exposing the cell support area outside the sealing zone to temperatures higher than 500 degrees C in air for more than 30 minutes; and (b) heating the un-sintered air electrode layer as applied to the cell to a temperature higher than 700 degrees C in the presence of a gas with a non-reducing composition while preventing exposure of the enclosed active area of the fuel electrode to the same gas by action of the seal and without any additional flow of gases containing hydrogen. INDEPENDENT CLAIMS are included for:    (1) a sealed solid oxide cell comprising a sintered air electrode prepared from the process;    (2) a process of preparing a solid oxide cell stack which involves: (a) preparing sealed solid oxide cells; (b) cutting inlet/outlet holes into the area of the sealed solid oxide cells and into the area of their adjoined interconnects; (c) applying an electrically non-conducting stack sealing material into the air electrode face of the solid oxide cells; and (d) stacking and sealing the cells; and    (3) a solid oxide cell stack prepared by the process.