Macroporous sulfonated polystyrene ion exchange resin was reacted with elemental fluorine in a liquid-phase suspension reactor at low temperature. This method gave retention of the bulk structure of the resin bead and resulted in a space-selective distribution of fluorine across the resin bead cross-section, as determined using F-19 secondary ion mass spectroscopy (LMI-SIMS). The polymer modification was additionally characterized using x-ray photo-electron spectroscopy, photoacoustic IR spectrophotometry, F-19, and C-13 MAS NMR spectrometry, and mercury porosimetry.