Sorption isotherms of prickly pear seeds were determined by static gravimetric method at temperatures 45º, 60º, and 70ºC, over a relative moisture range of 5-95%. Sorption isotherms are important to define dehydration limits of the product, estimate moisture content alterations under environment conditions, and to acquire moisture content values for safe storage. Four mathematical models were applied to analyze the experimental data. Equilibrium moisture contents of prickly pear seeds decreased with temperature increment at a constant value of relative humidity. The GAB model showed the best fitting to the experimental data. Isosteric heat and differential entropy, determined by applying the Clausius-Clapeyron and Gibbs-Helmholtz equations respectively, decreased strongly as the moisture content increased and could be well adjusted by an empirical exponential relationship. Enthalpy-entropy compensation theory is valid for the sorption of prickly pear seeds, in which the water sorption mechanism in seeds can be considered to be enthalpy controlled.