The adsorption equilibria relevant to the production of fructooligosaccharides were measured on Dowex Monosphere 99CA/320, Amberlite CR1320Ca, Lewatit S 2568, and Diaion UBK 530. The single-component isotherms of glucose, fructose, and sucrose and multicomponent isotherms of fructooligosaccharides (kestose, nystose, and fructofuranosylnystose) were obtained at a temperature of 60 degrees C and saccharide concentrations up to about 450 g.L-1. All but sucrose equilibrium data were described with a linear isotherm. The adsorption data of sucrose were successfully fitted using a concave isotherm. The capacities and selectivities of the adsorbents were compared. They showed that their separation effect was based on the size exclusion mechanism accompanied by complexation, which depended significantly on the resin's ionic form.