The retention kinetic of conjugated linoleic acid (CLA) and trans-vaccenic acid (TVA) in milk thermally treated was investigated in a temperature range of 90–120°C. Weibull distribution function was used to fit the experimental data and the results were evaluated through joint confidence regions. The shape parameter (β) was found to be independent of the temperature for both CLA and TVA, ranging from 0.48 to 0.76. The scale parameter (α) was affected by the temperature and its behaviour was described by an Arrhenius-type equation. The estimated activation energy (Ea) values were within the range of 151.3±13.1 and 99.6±12.3kJmol−1 for CLA and TVA, respectively. This kinetic information can be further used to design thermal processes, achieving high retention of bioactive lipids and identifying possible thermal treatment indicators.