A series of DABCO-functionalized polysulfones were synthesized and characterized. The effect that crosslinking has on the membrane properties containing different degrees of functionalization was evaluated. These polymers showed good thermal stability below the fuel cell operation temperature, T < 100 degrees C, reflected by the T-OD, T-FD, and thermal durability. The water uptake increased as the percentage of DABCO groups increased and the crosslinked membranes showed lower capacity to absorb water than the non-crosslinked ones favoring thus the dimensional stability of the first ones. Membranes in the chloride form containing low degree of functionalization exhibited the highest tensile strength values. The ionic conductivity of non-crosslinked membranes varied as a function of the functionalization degree until a value of around 100% achieving a maximum value at 86%. However, the crosslinked ones showed satisfactory ionic conductivities for values higher than 100%. The behavior of these polymeric materials in alkaline solutions revealed a great alkaline stability necessary to be used as solid electrolytes in fuel cells. (c) 2017 Wiley Periodicals, Inc.