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Phospholipids are the most important structural elements of the bacterial cell wall, participate in the adaptation of microorganisms to the environment and can act as biomarkers for environmental changes and one of the components of environmental monitoring. Native phospholipids are used to form models of cell membranes, the biophysical properties of which can be studied by the Langmuir-Blodgett method. The aim of this work was to isolate and characterize the phospholipids of the cell membranes of the bacteria Staphylococcus aureus and Bacillus cereus and the formation of Langmuir monolayers based on them. The composition and ratio of fatty acids were determined by gas-liquid chromatography of fatty acid methyl esters. Fatty acids, found in the extract of the bacteria S. aureus 209-P and B. cereus 8035, are: hexadecanoic, trans-9-octadecenoic, octadecanoic, tetradecanoic, 13-methyltetradecanoic, 14-methylpentadecanoic, 15-methylhexadecanoic, cis-9-octadecanoic. To form a monolayer, a working solution of native phospholipids in chloroform with a concentration of C = 10-3 М was used. The monolayer formed when a 50 μl solution of a phospholipid mixture is applied to the surface has a more perfect structure, which is manifested in the constancy of its mechanical properties. The analysis of the obtained data has not yet revealed a clear dependence of the monolayer parameters on temperature. The changes in the compression modulus and compressibility were very minor. With an increase in the salt concentration, both an increase and a decrease in the compression modulus, and, consequently, the rigidity of the monolayer, is observed.