Abstract: A method for evaluating the solubility of a crystalline substance in a polymer comprises a) providing at least one sample of an intimate crystalline substance/polymer mixture at a predetermined crystalline substance concentration; b) annealing the sample at a constant temperature Ta for a period of time; c) heating the annealed sample while recording the heat flux over time by DSC; d) identifying a DSC dissolution endotherm in the recorded heat flux, if any; e) considering the crystalline substance concentration as a concentration above the crystalline substance solubility in the polymer at temperature Ta when there is a DSC dissolution endotherm identified, and considering the crystalline substance concentration as a concentration less than or equal to the crystalline substance solubility in the polymer at temperature Ta when there is no DSC dissolution endotherm identified.