Porous silica beads were coated with a crosslinked P-cyclodextrin polymer by in situ polymerization/crosslinking of 2-hydroxypropyl beta-cyclodextrin with 1,6-hexamethylenediisocyanate in anhydrous dimethylsulfoxide. This method was developed for the preparation of reversed-phase high performance liquid chromatography stationary phases. The mass of polymer immobilized onto the silica surface was controlled by the amount of coupling agent, 1,6-hexamethylenediisocyanate, added during the coating process. The influence of the polymer coating on the physical features of the beads was investigated by means of nitrogen adsorption/desorption methods, scanning electron microscopy and energy dispersion X-ray analysis. The column lifetime was found to be primarily dependent on the extent of crosslinking of the stationary phase. Moreover, it was demonstrated that the synthesis of highly crosslinked stationary phases with a reasonable column lifetime gave rise to a phase separation of the beta-cyclodextrin polymer. To prove their usefulness as reversed-phase packing materials, they were used to separate mixtures of nitrophenol positional isomers, four pesticides, and drugs. (C) 2003 Wiley Periodicals, Inc. J AppI Polym Sci 91: 1419-1426, 2004.