The effect of different pH?s (3.4 to 9.0) on folic acid (PteGlu) stability during thermal (120-160°C) and high pressure thermal (400-800 MPa/20-60°C) processing was studied. The results showed that PteGlu showed to be very stable up to temperatures of 120°C. A pseudo first order kinetic model has been selected to describe the time-dependent changes in PteGlu concentration due to thermal treatments. During thermal treatment, PteGlu had the highest stability at neutral pH (pH 7.0) or alkaline pH (pH 9.2). The largest stability of PteGlu was found at pH 9.2 for thermal and pressure treatment and the stability decreased with increasing acidity.