The enzymatic hydrolysis was performed by Alcalase to recover the fish protein hydrolysate from Caspian kutum by-product (CB). The degree of hydrolysis (DH) was applied for monitoring the hydrolysis reaction of CB. The response surface methodology (RSM) was applied based on a D-optimal design to perform the optimization process for obtaining the high yield of CB protein hydrolysate. The effect of four independent variables including pH (7.5-8.5), temperature (45-55 °C), time (1-3 h), and enzyme concentration (0.5-1.5% w/w) on DH was studied. The results indicated that the predicted and actual values of the optimum condition had no significant difference. The optimum enzymatic hydrolysis conditions were achieved at pH 8.5, temperature of 55 °C, enzyme concentration of 1.5% w/w, and time of 3 2 h, which resulted in the maximum value of DH (19.08%). Antioxidant assays including DPPH scavenging and metal chelating activities showed that Caspian kutum protein hydrolysates (CKPH) had antioxidant properties.