Degradation of ceftazidime in aqueous solutions was studied at 298 K in acidic, basic and neutral conditions. The subsequent stage of hydrolysis involved the hydrolysis of the group at C-3, opening of the beta-lactam ring, and epimerization at C-6 or C-7. The decomposition of ceftazidime and the formation and identification of product C (pyridine) was followed by HPLC.