Lutein (Lut) has health beneficial properties, however, is poorly soluble in aqueous media and chemically unstable. The interaction with proteins, such as β-casein (β-CN), may overcome these limitations. The study of the thermodynamics of nanocomplex formation between β-CN-Lut is important to determine the stability of the nanocomplex and know the driving forces that drive this process, driving the future applications in the food field. Fluorescence spectroscopy was used (λ excitation = 295 nm and λ emission = 296 a 900 nm), pH 7.4, temperature range (20 to 36ºC), fixed concentration of β-CN (4 µM) and increasing Lut concentration (6.7x10-7 to 7.43x10-6 mol. L-1). The nanocomplex stoichiometry was, approximately 1, indicating that there is one Lut for each β-CN. The binding constants were of the order of 104 L.mol-1 for all temperatures studied. The values of the standard Gibbs free energy change were negative, showing that the formation of the nanocomplex was favored, being more stable at 32 ºC (ΔG° = -28.11 kJ.mol-1). In addition, it was observed that the increase in the temperature influenced the enthalpic and entropic contributions. For temperatures up to 26 ºC, the process was enthalpically driven (ΔHº = -7.35 kJ.mol-1), indicating that more energy was released from the β-CN-Lut specific interactions than was absorbed by the desolvation process of the free molecules in the solution. In contrast, for the upper temperatures (26 ºC), the entropic contribution dominated the process, being the greater absorption of the energy in the desolvation process at the temperature (32 ºC). There was enthalpic-entropic compensation for the formation of nanocomplex (α=0.9978 e R2= 0.9999), i.e., there was optimization of energy to form the nanocomplex. These results demonstrate that higher temperatures formed more stable β-CN-Lut nanocomplexes, providing useful information for Lut technological applications in different food matrixes.