Background: A conceptual equation to evaluate the Anderson–Grüneisen parameter (δ_T) has been used. This equation has been applied to estimate the parameter for the fatty acids with long carbon chain. Methods: For predicting the values of density (molar volume), volume thermal expansivity under isothermal condition and bulk modulus, it was used two cubic equation of state for the liquid phase. Peng-Robinson (P-R) was the one chosen to represent density behavior in accordance with the scarce experimental data for comparison. Results: For the three acids, Lauric, Palmitic and Stearic, Anderson–Grüneisen parameter was calculated, in two range of pressures (1-10atm; 30-50atm) and in a range of temperature of 350-450 K. Conclusion: Despite there are no experimental data available in the literature, these results are found to be consistent with the thermodynamic constraints.