Surfaces that exhibit the reactivity of silica toward surface modification (silanol condensation) were prepared by treating thin films and particles of poly(methylsilsesquioxane) with aqueous potassium persulfate at elevated temperature. Parallel experiments were carried out using a highly cross-linked poly(dimethylsiloxane). Advancing (θA) and receding (θR) water contact angles for all of these oxidized surfaces were θA/θR = ∼10/∼0°, and these low values remain unchanged for months. Reactions of these silica-like surfaces with a range of functional silane reagents indicate that the surface silanol concentration is sufficient to prepare covalently attached monolayers of similar surface density to those prepared using silicon wafers as substrates.