Pacific oyster muscle hydrolysates were prepared by pressurized hot water extraction (PHWE) at process conditions ranging 125 degrees C/20 bar similar to 275 degrees C/140 bar to investigate various physico-chemical and bio-functional parameters. Degree of hydrolysis was increased with increasing temperature and pressure and at 275 degrees C/140 bar, hydrolysis was found to be highest. Glycogen, protein, reducing sugar, and phenolic content of the hydrolysates were increased obtained from 125 degrees C/20 bar to 225 degrees C/100 bar, but decreased after raising over 250 degrees C/120 bar. Total and free amino acid contents were subsequently decreased as temperature and pressure increased over 175 degrees C/60 bar. Radical scavenging activity and antihypertensive activity was found to be highest at 225 degrees C/100 bar at which condition, the protein molecular size and carbohydrate molecular weight of the hydrolysates were 15 kDa or lower and 300-1000 Da, respectively. This study suggests the 225 degrees C/120 bar conditions for bio-functional Pacific oyster hydrolysate preparation .