Poly(ether ether ketone) with pendent sulfonimide groups (B-SPEEK) was prepared from poly(ether ether ketone), sulfuric acid, thionyl chloride, para-toluene sulfonate, and pyridine. The prepared B-SPEEK was characterized by Fourier transform infrared spectroscopy, H-1-NMR, and thermogravimetric analysis. The swelling of the gels was examined in N, N-dimethylacetamide (DMAC), N, N-dimethylformamide (DMF), 1-methyl-2-pyrrolidinone (NMP), dimethyl sulfoxide (DMSO), and a DMSO/water mixture. The gel showed extremely high swelling in DMSO, DMF, DMAC, and NMP. (C) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1058-1063, 2013