NOVELTY - The cell (2) has a partial membrane electrode assembly (MEA) (160, 160') provided with a partial membrane (161), partial reaction surfaces (174) and low gas diffusion layers (176, 177). Cooling medium modules (164, 164'165, 165', 166, 166') comprise a low hydrogen gas segment (180) and a low carbon dioxide gas segment (181). The cell and multiple partial cells (173, 173') are integratedly connected in series. Current conductors are formed as current paths (81, 81') and/or partial stream paths (169) and integrated into the cell stack. Multiple stack lines are arranged in the partial cells.    USE - Fuel cell i.e. phosphoric acid fuel cell, for use in a cell stack i.e. electrolyzer, that is utilized for producing gas e.g. hydrogen and oxygen, from water (all claimed).    ADVANTAGE - The current conductors are formed as the current paths and/or the partial stream paths and integrated into the cell stack, and the stack lines are arranged in the partial cells, thus avoiding requirement of bipolar plates electric resistors, and hence reducing dimensions of the fuel cell to simplify assembly and operation of the fuel cell while avoiding electrochemical phenomena i.e. peak or intense electrochemical reactions, on the reaction surface of the partial cells with reduced effort. The cell and multiple partial cells are integratedly connected in series, thus optimizing thermodynamic properties of the fuel cell. The fuel cell is designed such that optimum dissipation of process heat, gas utilization and power generation is ensured in the fuel cell.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a cell stack.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of a stack section of a cell stack with a fuel cell.    Fuel cell (2)    Current paths (81, 81')    Partial MEA (160, 160')    Partial membrane (161)    Cooling medium modules (164, 164'165, 165', 166, 166')    Partial stream paths (169)    Partial cells (173, 173')    Partial reaction surfaces (174)    Low gas diffusion layers (176, 177)    Low hydrogen gas segment (180)    Low carbon dioxide gas segment (181)