Orange juice is the most popular juice in the world, representing an important source of bioactive compounds in diet. High hydrostatic pressure (HHP) is an alternative technology that does not use high temperature, being able to preserve flavor and nutritional characteristics of the juice. The influence of HHP treatment conditions, pressure (100-600 MPa), temperature (30- 60°C) and time (30-360 s), on ascorbic acid, phenolic compounds and antioxidant activity of orange juice was investigated using response surface methodology. Analysis of variance showed that quadratic polynomial models fitted well with the experimental data for ascorbic acid (R²=0.92, p