Sunset yellow (SY) dye removal from aqueous solution was assessed by ultrasound/peroxymonosulfate/ CuFe2O4 nanoparticles. CuFe2O4 nanoparticles were synthesized and their properties were well determined by several advanced techniques. The effects of pH, catalyst dosage, peroxymonosulfate (PMS) concentration, and ultrasound (US) intensity were investigated on the decolorization. The best results (95.8% removal) were observed at pH=7, CuFe2O4= 25mg/L, PMS=1.5mM, US=200 W and 30 min. Nitrite and bicarbonate ions demonstrated high inhibition effect on the decolorization. PMS depicted high activity in the presence of CuFe2O4 compared to S2O8 2- and H2O2. Around 40% reduction in the decolorization was observed in reusability experiments. Sulfate and hydroxyl radicals were the major species of SY degradation based on quenching experiments. A mineralization of 50% was obtained only in 30min reaction time. This process can be effective for the destruction of organic dyes in colored wastewater.