Abstract: The present invention relates to high-temperature solid oxide fuel cells, in particular to rotationally symmetrical high-temperature solid oxide fuel cells. The inventive oxide-ceramic high-temperature fuel cell having one or more gas channel(s) open at at least one end. The fuel cell has a substrate surrounding the gas channel(s) at least sectionally, preferably completely. The gas channel(s) and/or the substrate surrounding the gas channel(s) has/have (a) changing cross-sections(s), preferably (a) conically tapering cross-section(s), seen in the direction of the longitudinal axis/axes of the gas channel(s).