Vitamin C and vitamin D-3 perform different and important activities in living systems. Vitamin D-3 forms stable monomolecular films at the gas/water interface and, at higher concentrations, produces large aggregates in water solutions. Because of their amphiphilic structure, vitamin C alkyl esters form monolayers, micelles, vesicles, or microemulsions in water, depending on composition, concentration, solvent, and temperature. In this work the monolayer of 6-O-ascorbyl-stearate and vitamin D-3 was Studied to investigate the behavior of the two compounds and their mixtures at the gas/water interface at different temperatures, at different pH, and in the presence of Ca2+ in the subphase. The results show that stable Langmuir films are formed in all molar ratios, with repulsive interactions between the two components, and that the presence of calcium ions modifies the properties of the monolayer.