In this study, copper(I) sulfide (Cu2 degrees S) nanoparticles were easily synthesized via thermal decomposition of Cu(II) diethyldithiocarbamate complex at 220 degrees C. Characterization by a variety of spectroscopic and physical techniques confirmed that the obtained product was pure Cu2S composed of about 50 nm nanoparticles. An ultrasound-assisted advanced oxidation process (AOP) was developed for the degradation of methylene blue (MB) over the Cu2S nanoparticles. The ultrasound-assisted H2O2/Cu2S catalysis removed 100% MB (25 mg L-1) in 12 min with an apparent rate constant of 0.268 min(-1), which is 193 and 27.5 folds of that in the simple catalytic H2O2/Cu2S and US/H2O2 systems, respectively. The synergistic behavior between Cu2S catalysis and ultrasound waves was demonstrated to be dependent on Cu2S dosage and H2O2 concentration. Trapping experiments indicated that (OH)-O-center dot radicals were the main reactive species for MB degradation in the present sonocatalytic system. Furthermore, the cycling experiments revealed the good stability of Cu2S nanoparticles. (C) 2016 Elsevier Ltd. All rights reserved.