Abstract: The preparation of a silica-based packing for the aqueous size Exclusion Chro-matography (SEC) is described. The process involved the hydrogen-bonding of a coupling reagent with the silica gel surface followed by ring-openning reactions of the epoxy groups on the coupling reagent molecules by polyethylene glycols. The results show that this modified packing can be used for the SECanalysis of polyvinyl acetate, gelatins, proteins and dextran systems.