Abstract: Sulfobenzylsilicas in which the organic moiety is bound to silica surfaces through a carbon-silicon bond are prepared by treating silica with thionyl chloride to chlorinate reactive silanol groups, reacting the product with benzyllithium and sulfonating the resulting benzylsilica. The sulfobenzylsilicas and their salts of noble metals are useful as bound stationary phases in various chromatographic procedures for the separation of a wide variety of natural product mixtures composed of closely related chemical compounds. For example, separation of methyl cis 9-octadecenoate and methyl trans 9-octadecenoate was readily achieved by gas-liquid chromatography on a modified silver sulfobenzylsilica column.