NOVELTY - The cell (10) comprises: a tubular carrier body (11) with a hollow cylindrical intermediate portion (111) and two end portions; and a functional layer system including an oxygen electrode layer (12), a fuel gas electrode layer (13), and an electrolyte layer formed between the electrode layers. The intermediate portion is made of a gas-tight, oxygen ion-conductive material or a gas permeable porous ceramic material. One of the end portions is made of a gas-tight, non-oxygen-conductive material, and is adapted for mounting the cell.    USE - The tubular electrolysis cell such as combined electrolysis and fuel cell, is useful in an energy system such as photovoltaic system, wind power plant, biogas plant, residential or commercial building, industrial plant, power station and vehicle (all claimed).    DETAILED DESCRIPTION - The cell (10) comprises: a tubular carrier body (11) with a hollow cylindrical intermediate portion (111) and two end portions; and a functional layer system including an oxygen electrode layer (12), a fuel gas electrode layer (13), and an electrolyte layer formed between the electrode layers. The intermediate portion is made of a gas-tight, oxygen ion-conductive material or a gas permeable porous ceramic material. One of the end portions is made of a gas-tight, non-oxygen-conductive material, and is adapted for mounting the cell. The other end portion is a cap-shaped end portion made of a gas-tight, non-oxygen-conductive, electrically insulating material. The electrolyte layer has a layer thickness of 15-300 mu m. The cap-shaped end portion is laid out on the mounting end portion. A tongue and groove-like toothing is formed between the mounting end portion and the hollow-cylindrical intermediate portion. The cup-shaped end portion is distributed with indents and/or struts whose diameter along a symmetry axis of the intermediate portion is decreased towards a center of the cup-shaped end portion. An interconnector made of an electrically conductive material, a planar interconnect made of a gas permeable, electrically conductive material, and a web-shaped interconnector made of a gas permeable or gas-tight electrically conductive material, are arranged between the electrode layers. An INDEPENDENT CLAIM is included for a method for producing a tubular electrolysis cell.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic cross-sectional view of an electrolysis cell.    Electrolysis cell (10)    Carrier body (11)    Oxygen electrode layer (12)    Fuel gas electrode layer (13)    Intermediate portion. (111)