NOVELTY - Sulfonated polyimides, ion-exchange membranes and fuel cells are new.    USE - In production of ion exchange, ion conducting membranes for use in low temperature fuel cells (especially membranes separating anode and cathode compartments of cells working in systems comprising hydrogen, alcohols (methanol) for anode, and oxygen, air for cathode).    ADVANTAGE - High chemical and electrochemical resistance of membranes increases service life of fuel cell.    DETAILED DESCRIPTION - Sulfonated polyimides are formed of sequences or blocks represented by formulae (Ix) and (Iy)    x = at least 4, preferably 4-15;    y = at least 5, preferably 5-40;    C1 and C2 = identical or different tetravalent groups comprising at least one 6-10C aromatic cycle, optionally substituted and/or 5-10 atoms heterocycle of aromatic type, optionally substituted, and comprising one or more heteroatoms selected from S, N and O; with C1 and C2 each forming 5 or 6 atoms cycles with adjacent imide groups;    Ar1 and Ar2 = identical or different divalent group comprising at least one 6-10C aromatic cycle, optionally substituted and/or 5-10 atoms heterocycle of aromatic type, optionally substituted, and comprising one or more heteroatoms selected from S, N and O, with at least one of aromatic cycles and/or heterocycles of Ar2 substituted with at least one sulfonic group    . Sulfonated polyimide has general formula (I)    C1, C2, Ar1, Ar2, x and y = as described for (Ix) and (Iy);    R2 and R2 = NH2 or group (II);    C3 = divalent group comprising at least one 6-10C aromatic cycle, optionally substituted and/or 5-10 atoms heterocycle of aromatic type, optionally substituted, and comprising one or more heteroatoms selected from S, N and O; and it forms 5 or 6 atoms cycle with adjacent imide group;    z = 1-10    (Full definitions given in DEFINITIONS (Full definitions) Field). INDEPENDENT CLAIMS are also included for 1) membrane comprising sulfonated polyimide as claimed; and 2) fuel cell comprising at least one membrane as claimed.    DESCRIPTION OF DRAWING(S) - The drawing represents schematic view of fuel cell.    solid polymeric electrolyte (1)    anode space (2)    cathode space (3)    hydrogen (4)    air oxygen (5)    water (6)    watertight plates (7,8)    transported protons (9)    external circuit (10)    diffusion-osmosis arrows (11, 12)    volume electrodes (13)    active zone (14)    diffusion zone (15)    platinum grains (16)    electrons (17)    electric engine (18)