NOVELTY - The electrolyzer having anionic conduction comprises an electrochemical cell (10) formed by: a solid electrolyte (13) formed by a ceramics; a first electrode (11) forming an anode of the electrochemical cell; and a second electrode (12) forming a cathode of the electrochemical cell. The electrolyte is placed between the first electrode and the second electrode. The solid electrolyte is made of zirconium oxide doped by erbium oxide. The first electrode and the second electrode are a metal electrode or a ceramic electrode.    USE - The electrolyzer is useful for generating hydrogen and oxygen by steam electrolysis at high temperature (claimed), and for treating carbonaceous gases (carbon dioxide and carbon monoxide) by electrochemical hydrogenation, where the electrolyzer is a solid oxide electrolyzer cell.    ADVANTAGE - The electrolyzer is free from the phenomena of decomposition and delamination of electrolyte/electrode interfaces of the electrochemical cell thus improving electrochemical performances and prolonging service life of the electrolyzer.    DETAILED DESCRIPTION - The electrolyzer having anionic conduction comprises an electrochemical cell (10) formed by: a solid electrolyte (13) formed by a ceramics; a first electrode (11) forming an anode of the electrochemical cell; and a second electrode (12) forming a cathode of the electrochemical cell. The electrolyte is placed between the first electrode and the second electrode. The solid electrolyte is made of zirconium oxide doped by erbium oxide. The first electrode and the second electrode are a metal electrode or a ceramic electrode. The first electrode and the second electrode are formed by a cermet. The cermet includes a mixture of a ceramics and an electronically conducting alloy to form a passive layer, where the nature and content of the metallic alloy is determined so that a melting temperature of the alloy is greater than a sintering temperature of the electrolyte. The electrochemical cell has an assembly electrode/electrolyte/symmetrical electrode. An INDEPENDENT CLAIM is included for a method for generating hydrogen and oxygen by steam electrolysis at high temperature.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic sectional view of an electrochemical cell.    Electrochemical cell (10)    First electrode (11)    Second electrode (12)    Solid electrolyte. (13)