The degradation of sulfamethoxazole (SMX) was investigated under the sono-catalytic ozonation process over magnetic suspension. The effects of various operating conditions were investigated, including initial pH value, catalyst dosage, and power density. The results indicated that the degradation of SMX followed a pseudo-first-order kinetic model under different operating conditions. The removal rate increased with the increase of pH, but it decreased when the catalyst dosage or power density exceeded a certain value. The removal rate was inhibited in the presence of tert-butyl alcohol, isopropanol or NaF. After 20 min treatment, the COD removal reached 57.5%, the acute toxicity to Daphnia magna largely decreased, and the biodegradability (BOD5/COD ratio) increased from 0.02 to 0.41. COD was almost completely removed when the reaction time was extended to 120 min. (c) 2013 Elsevier B.V. All rights reserved.