The synthetic resin Amberlite IR-120 in the Na+ form (10 cm3), and the naturally occurring zeolite, clinoptilolite, (20 cm3) have been found to quantitatively remove trimethyllead (TriML) from aqueous solutions of ionic strength up to 10(-2) M NaCl. Elution by 150 cm3 2.7 M NaCl removes the TriML back into solution, from where it can be extracted, derivatized with propyl Grignard reagent and analyzed by GC-AAS. TriML is stable for at least 24 h on the ion-exchange media. The method allows the sampling and determination of TriML in natural and wastewaters with a detection limit of 0.1 ng (Pb) dm-3. It may also be used for the decontamination of wastewaters. This technique may be applicable to other ionic organometallic compounds, including tributyltin.