In this dissertation, equilibrium studies of adsorption of phenolic acids (gallic, p-coumaric, caffeic, chlorogenic acid), flavan-3-ols (procyanidin B1 and B2), dihydrocalcones (floretin, floretin-2-glucoside) and anthocyanins (cyanidin-3-glucoside, cyanidin-3-galactoside) onto dietary fiber (β-glucan) at different temperatures and pH values of the medium are carried out. The results are modeled with adsorption isotherm equations by nonlinear regression. For the purpose of the kinetic research, adsorption was examined in different time periods, and the data were analyzed with kinetic models of pseudo-first and pseudo-second order. Gallic acid showed a higher adsorption capacity than p-coumaric, caffeic and chlorogenic acids which can be caused by a larger number of OH groups on the molecule. Procyanidin B1 and B2 showed similar adsorption capacity. Cyanidin-3-glucoside had a slightly higher adsorption capacity than cyanidin-3-galactoside, and floretin-2-glucoside than floretin, which may have been affected by glycosylation of the molecule. Adsorption was a spontaneous and exothermic process and probably follows pseudo-second order kinetics and the half-life is between 0.76 and 7.22 h. Scanned UV/Vis spectra confirmed the existence of interactions between polyphenols and β-glucan. The existence of differences in adsorption capacities at different pH can be explained by different forms of polyphenols. The proportion of non-protonated and protonated functional groups is important for phenolic acids, glycosylation is important for dihydrocalcones, and structural differences at different pH for anthocyanins. The parameters of the adsorption isotherms indicate physical adsorption with H-bonds and van der Waals forces between polyphenols and β-glucans, with negative cooperation in binding at all temperatures and pH values. Adsorption of polyphenols from the flesh and peel of apples was also performed, and in such a real system consisting of several different polyphenols, adsorption was concentration dependent (higher concentration yielding higher adsorption capacity), with hydrogen bonds or van der Waals forces between polyphenols and β-glucan again indicated. The conducted studies provided a better insight into the interactions between polyphenolic compounds and dietary fiber which are important for explaining the bioactivity of polyphenolic compounds.