Rice bran was used for isolating protein through ultrasonic-assisted extraction. The protein was converted into protein hydrolysates (PH) with three commercial enzymes. The optimal condition for rice bran protein production was 76% sonication amplitude, 18 min extraction and 0.99 g/10 mL solid–liquid ratio, which gave protein yield of 4.73 ± 0.03%. The degree of hydrolysis for the rice bran protein by Subtilisin A (SPH), Actinase E (APH) and Neutrase 0.8L (NPH) was 20.03 ± 0.24%, 13.84 ± 0.04% and 5.54 ± 0.07%, respectively. The molecular weight of the isolated proteins ranged between