The aim of this master-degree work was studying excess adsorption isotherms of organic solvents: acetonitrile and methanol, from water. Five commercially available chemically-bonded stationary phases, i.e. five chromatographic colums (Kinetex™ columns: Phenyl-Hexyl, Biphenyl, C18, XB C18 and PFP, made by Phenomenex®), were used. These columns were characterized by different functional groups. Excess adsorption isotherms were measured using the minor disturbance method under UPLC conditions. These isotherms provided useful information about structure of the stationary phases. Measured parameters of the solvent peaks were the basis for making excess isotherms. Therefore, excess of organic solvent or water was injected. The amount of "adsorbed solvent" can indicate the type of distribution mechanism. Also, the influence of temperature on the preferential adsorption was measured on Phenyl-Hexyl columns. Based on the resulting excess adsorption isotherms, it was confirmed that molecules of acetonitrile had more affinity for observed stationary phases and they interacted by π-π interactions. Methanol and water formed hydrogen bonds with polar and residual silanol groups on stationary phases. By comparing excess adsorption isotherms for acetonitrile and methanol, one can observe that the adsorption of acetonitrile is approximately 3 times higher than adsorption of methanol, and negative part for adsorption of water in the system of acetonitrile–water is about 5 times above the one in methanol–water system. The adsorption of acetonitrile decreases with the increase of temperature and the optimal temperature for adsorption is 20 °C.