NOVELTY - A solid oxide electrochemical cell comprises a solid oxide electrolyte layer (11) sandwiched between a hydrogen electrode (12) and an oxygen electrode (13). The hydrogen electrode comprises an oxide sinter having fine metal particles (16) deposited on its surface, which is coated with a film having mixed conductivity; and a sinter having ionic conductivity.    USE - As a solid oxide electrochemical cell such as e.g. solid oxide fuel cell (SOFC) and a solid oxide electrolysis cell (SOEC).    ADVANTAGE - The solid oxide electrochemical cell exhibits improved output characteristics such as power density, and ohmic resistance.    DETAILED DESCRIPTION - A solid oxide electrochemical cell comprises a solid oxide electrolyte layer (11) having ionic conductivity, a hydrogen electrode (12) formed on one side of the electrolyte layer, and an oxygen electrode (13) formed on the other side of the electrolyte layer so that the electrolyte layer is sandwiched between the electrodes. The hydrogen electrode comprises an oxide sinter having fine metal particles (16) deposited on its surface, which is coated with a film having mixed conductivity; and a sinter having ionic conductivity. The cell further comprises a current collector (14) and in which the hydrogen electrode has a conductive layer having a porosity of 30-80% and comprising a mixture comprising at least one metal material selected from platinum (Pt), gold (Au), silver (Ag), nickel (Ni), iron (Fe), cobalt (Co) and/or copper (Cu) or their alloy, and an ion conductive material or a material having electron/ion mixed conductivity, which materials constitute the hydrogen electrode. The conductive layer is formed by of a screen printing method, a splay coating method or a vapor deposition method and the area occupied by the conductive layer accounts for 40-100% of the hydrogen electrode surface. An INDEPENDENT CLAIM is included for producing the solid oxide electrochemical cell involving either superposing a layer of a mixture of an oxide solid solution, at least one metal salt, and the sinter having ionic conductivity on the solid oxide electrolyte layer; subsequently sintering the layer to form the film having mixed conductivity on the surface of the oxide solid solution and on the surface of the sinter having ionic conductivity, where the film with mixed conductivity is made of an oxide of the metal salt; and then reducing the layer at 800-1000 degrees C to change the oxide solid solution into the oxide sinter having fine metal particles exposed on the surface; or sintering a mixture of an oxide solid solution and at least one metal salt to form a coating film having mixed conductivity on the surface of the oxide solid solution; superposing a layer of a mixture of the resultant coated oxide solid solution and the sinter having ionic conductivity on the solid oxide electrolyte layer; and then sintering the layer superposed and reducing the sintered layer at 800-1000 degrees C to change the oxide solid solution into the oxide sinter having fine metal particles exposed on the surface.    DESCRIPTION OF DRAWING(S) - The figure shows a sectional view of the structure of the solid oxide fuel cell (SOFC).    Solid oxide electrolyte layer (11)    Hydrogen electrode (12)    Oxygen electrode (13)    Current collector (14)    Fine metal particles (16)    Supporting alumina (17)