Sodium phosphate salts are widely used in the manufacture of processed cheese for the stabilization of casein, as well as to improve the texture and functionality of the final cheese. The essential role involves calcium sequestering and pH control leading to the hydration and dispersion of casein, which in turn allows it to act as emulsifying agent resulting in the formation of a homogeneous cheese structure. During the processing phosphates may undergo hydrolysis due to heat treatment, pH and ionic environment. The formation of short chain phosphates increases the buffering capacity of the medium and therefore affects the final pH of the processed cheese. The objective of this study was to investigate the impact of temperature on the hydrolysis of sodium tripolyphosphate (STPP) in milk. Milk with 2.3% STPP was heated to 90°C and cooled to 5°C and the nuclear magnetic resonance (NMR) spectra were obtained at 5°C intervals. ³¹P NMR spectroscopy was performed using a double resonance probe, fitted with a field gradient in the Z direction, coupled to a Bruker AVANCE III, operating at 14.1 T static magnetic field (500 MHz for ¹H). The spectra were processed with the aid of TOPSPIN 3.1 software. STPP hydrolysis occurred for the entire temperature range during milk heating and cooling and was significantly more intense from 80°C. At 90°C, 20.5% of STPP was hydrolyzed resulting in a 33.5% increase in the amount of pyrophosphate and orthophosphate. The spectra also showed a shift from left to right, indicating that the STPP hydrolysis resulted in a more acidic environment, which can affect the rate of hydrolysis. Knowledge of the phosphates behavior during processing can lead to a better understanding of the changes associated with the protein matrix of processed cheeses and its functional properties. Acknowledgment: São Paulo Research Foundation (FAPESP), grant 14/07291–3.