The degradation of tetracycline was investigated using the ultrasound-enhanced magnetite catalytic ozonation process (US/Fe3O4/O-3). Thorough assessments of the operational parameters, biodegradability and acute toxicity were performed. The results indicated that the TC degradation rate was strongly influenced by the initial pH and the ultrasonic power density over the range investigated, but it was almost independent of the dosage of Fe3O4 in the range of 0.3-1.0 g L-1. The TC degradation rate was diminished in the presence of tert-butanol, isopropanol and NaF. Under the optimal conditions, TC was almost completely removed after 20 min of treatment, and the COD removal reached 41.8%. The COD removal further increased to 89.1% when the reaction time was extended to 120 min, and the corresponding biochemical degradability (BOD5/COD) rose to 0.694. The acute toxicity reached its maximum value after 60 min treatment and then decreased with the prolonged reaction time. The catalyst stability was evaluated by measuring the TC removal rate and iron leaching for three successive cycles. (C) 2013 Elsevier B.V. All rights reserved.