A novel efficient method for hydrolyzing feather keratin using an ultrasonic-ionic liquid coupling process has been developed, with reaction conditions optimized using response surface analysis of data obtained from single factor optimization studies. Ultrasonic irradiation (225 W power) of feathers in 8.4 mol.L-1 hydrochloric acid containing 1-butyl-3-methylimidazolium chloride as a cosolvent at 80 degrees C for 1.4 h, followed by heating at 110 degrees C for 8.3 h, resulted in hydrolysis of their keratin component in an excellent 83.1% yield. Compared with previous methods, this new method employs reduced amounts of hydrochloric acid, shorter reaction time, and affords amino acid hydrolysis products in higher yield. (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.