The stability of the native structure of gelatin in solution is affected by the presence of desolvating agents, temperature and pH of the solution. When sufficient desolvation is obtained, the gelatin molecules begin to aggregate, resulting in phase separation, forming a coacervate or, if excessive desolvation is applied, a precipitate. The objective of this study was to determine the effect of the desolvating agents ethanol and sodium sulfate on the distribution of molecular weight species between the two phases. We believe that the characterization of this behavior is crucial in order to optimize the conditions required for the formation of gelatin nanoparticles.