BACKGROUND: The removal of antibiotic ampicillin sodium using H 2 O 2 and modified granular activated carbon (GAC) is discussed. Two types of modified activated carbons were used in experiment to catalyze ·OH production from H 2 O 2 . One was modified with base (NaOH; called B-GAC), the other was modified with Fe(NO 3 ) 3 (Fe-GAC) and the nominal Fe metal loading was 5 wt%. In the experiment, pH, contact time, dosage of activated carbon and H 2 O 2 and initial concentration of ampicillin sodium were investigated to determine their influence on the removal efficiency. The stability of Fe-GAC was also evaluated.