Project Description. This investigation proyect is concerned about the formation of polyethylenimine-Albumin complexes as an alternative to avoid structural changes of protein during thermal changes. The structural changes of free protein and complexes were induced by increasing the temperature of both systems. We show that changes in the structure of protein were attenuated when the polyethylenimine acts as complexing agent. The structural changes in both systems were measuring by Raman spectroscopy, Fluorescence and Circular Dichroism. Our results show that the Raman technique is capable to measure structural changes in free Albumine and in complexes with PEI.