Lactoferrin is a globular protein from milk that has considerable potential as a functional ingredient in food, cosmetic and pharmaceutical applications. In this study, we examined the possibility of preparing food-grade bovine lactoferrin (bLf) nanoparticles using a simple thermal processing method. Differential Scanning Calorimetry (DSC), light scattering, and ζ-potential techniques were used to provide information about the conformational changes, aggregation, and electrical charge of bLf in aqueous solutions. DSC studies indicated that the protein had two thermal denaturation temperatures (61 and 93 °C), which were associated with two different lobes of the protein. Protein denaturation was found to be irreversible, which was attributed to the formation of protein nanoparticles, whose size depended on the temperature and duration of the thermal treatment. Higher holding temperatures produced faster protein aggregation and larger protein nanoparticles: 85 > 80 > 75 > 70 °C. The protein nanoparticles produced by thermal treatment were resistant to subsequent changes in pH (from 3 to 11) and to salt addition (0–200 mM NaCl). The lactoferrin nanoparticles produced in this study may be useful as function ingredients in commercial products.Graphical abstract