The purpose of this contribution is to compare the quality of adsorbed films of CH3-(CH2)(n)-SiCl3 and CH3-(CH2)n-PO(OH)(2), n = 4 and 13. Mechanically polished polycrystalline titanium substrates were reacted with 10(-3) M solutions of the compounds in ethanol for the n-alkanephosphonic acids and in toluene for the n-alkyltrichlorosilanes. Assessments of the films have been carried out with X-ray photoelectron spectroscopy (XPS), contact angle measurements and electrochemical impedance spectroscopy (EIS). n-Alkyltrichlorosilanes form better quality monolayers than n-alkanephosphonic acids. (C) 2003 Elsevier Science B.V. All rights reserved.