Silanization of macroporous glass microfiber filters with (3-aminopropyl)triethoxysilane (APTES) and subsequent binding of [2-(3 4-epoxycyclohexyl)ethyl]heptaisobutyloctasilsesquioxane (E-POSS) to the amine-terminated surface of microfibers was studied. Prior to the silanization, minute quantities of concentrated aqueous Solutions of hydrochloric acid or ammonia were adsorbed in the filters while attachment of E-POSS molecules to APTES overlay was not specially catalyzed. Analysis of DRIFT, XPS, and C-13 CP/MAS NMR spectra has shown that the formation of APTES overlay is affected differently by the surface-deposited acid or base. It was proved by XPS that microfibers with the adsorbed acid take up higher amounts of covalently attached APTES by 42% and, Subsequently, of E-POSS by 65% than microfibers with the adsorbed ammonia. The molecular mechanics model Calculations, which were made using silica as a template, have shown that approximately two-layered APTES coating can be built on the model surface if complete hydrolysis of ethoxy groups and vertical condensation of APTES species are assumed.