Supramolecular self‐assembly of polystyrene–poly(vinylpyridine) diblock copolymers adsorbed from a selective solvent onto smooth substrates was used to create surfaces with regularly varying chemical composition. Well‐ordered arrays of localized chemical reaction sites are formed on such surfaces with sizes and intersite distances of molecular length scales. We demonstrate site‐specific complex formation with transition metal salts resulting in a nanoscopic ordered array of metal salt–polymer complexes. Selective etching of the metal‐loaded microdomains is shown. The effect of block copolymer molecular architecture on the supramolecular structure of these ‘‘chemically functionalized’’ surfaces was studied. ©1996 American Institute of Physics.