We demonstrated an acetalization reaction as a versatile method to immobilize aromatic aldehyde molecules on surfaces of metal oxides, silicon dioxide. and indium tin oxide. First, a trimethylsily (TMS) terminated surface was formed using a silylation reaction between a chloride group of trimethylsilychloride and a hydroxyl group of the substrate surfaces. Second, terephthalaldehyde (TPA) was immobilized on the surfaces using an acetalization reaction between the TMS-terminated surface and an aldehyde group of TPA. Results of contact angle, X-ray photoelectron. and ultraviolet absorption spectra revealed that the TPA molecules on the surfaces were well-packed with a high surface density. (C) 2009 Elsevier B.V. All rights reserved.