Radiation crosslinked poly(ethylene oxide)s (PEG) modified with two tetraalkylammonium salts : allyldimethyldodecylammonium bromide and ethylmethacrylate dimethyldodecylammonium bromide were prepared. They have been characterized by elemental analysis, IR, H-1-NMR spectra, and DSC measurements. Their activity as phase transfer catalysts (PTC) in the model displacement reaction of 1-bromooctane with aqueous sodium cyanide were studied. The reaction kinetics were followed under pseudo-first-order conditions. Small amounts of onium salt inserted into the PEO network gave rise to a five time increase in the rate constant. The recovered catalysts could be re-used without loss of activity.