In this work, the surface hydrolysis of postconsumer polyethylene terephthalate (PET) was used to produce an ion exchange material to adsorb cationic contaminants from water. The PET surface hydrolyses were carried out in neutral, alkaline, and acid media (NaOH or HNO3 at 7, 10, and 15 mol L-1) under reflux producing surface carboxylic acid sites (-COOH) characterized by ATR-IR, pyridine adsorption, titration, TG, and DSC analyses. Acid hydrolysis produced high concentrations of -COOH (up to 0.5 mmol g(PET)(-1)), whereas no significant concentration of carboxylic acid sites was obtained by neutral and alkaline hydrolysis. SEM analyses suggest that the acid sites are likely located at the