Aerosols in the troposphere influence the Earth s climate. The ability of aerosols to activate or act as a cloud condensation nucleus inducing the transformation into a raindrop depends on their physicochemical properties. In this dissertation, mixed Langmuir films of stearic acid and amino acids are used as templates to the surface of atmospheric aerosol particles. The amino acids used in the experiments were: L-Phenylalanine, L-Tryptophan, L-Leucine, L-Isoleucine, L-Methionine, L-Lysine and L-Histidine. They were chosen due to their different characteristics of hydrophobicity, water solubility, and polarity. This study aimed to understand how amino acids affect the surface pressure (pi) and the surface potential (delta V) of Langmuir films of stearic acid in aqueous solution-air interface, inducing morphological changes. The characterization of the films was performed by experiments of surface pressure and surface potential of the mixed film, which were carried out in a Langmuir minimicro trough coupled to a Wilhelmy balance and a surface potential sensor. According to the results obtained in the surface potential and surface pressure experiments, it was observed that the presence of these amino acids stearic acid film decreases the collapse pressure of the stearic acid film. In the films formed with L-Phenylalanine and L-Lysine, hysteresis was observed in all compressions. On the other hand, L-Leucine, L-Isoleucine, L-Histidine, L-Methionine and L-Tryptophan showed no hysteresis.