Polyethersulfone (PES) fibrous mats were prepared using the electrospinning method and subsequently characterized. The electrospinning preparation conditions that provided the highest quality PES fibrous mats were the following: a concentration of 30 wt.% of PES, 3 mL/h flow rate, 15 cm of tip to collector distance (TCD) and 15 kV of applied voltage. The specific surface area measured using the BET method tended to decrease as the thickness of the fibers increased. The PES fibrous mats electrospun with the optimized preparation conditions were sulfonated for 30-150 min. The structures of the PBS and sPES (sulfonated PES) were characterized using Fourier transform infrared (FOR) spectroscopy. The DS (degree of sulfonation) and ion exchange capacity were proportionate to the sulfonation time. Water uptake increased and contact angle values decreased as the DS increased because of the increased hydrophilicity of sPES. The sPES fibrous mats were thermally stable at temperatures up to 280 degrees C. The sorption isotherm of ammonium was applied to the Langmuir and Freundlich models. (C) 2012 Elsevier B.V. All rights reserved.