This paper compares the properties of self-assembled monolayers (SAMs) on polycrystalline gold formed at 24-degrees-C from 1 to 1000 muM ethanolic solutions of dialkyl disulfides and of alkanethiols. The paper also describes an exploratory study of the kinetics of formation of these SAMs. The SAMs were characterized by ellipsometry, X-ray photoelectron spectroscopy (XPS), and wettability by water or hexadecane. SAMs derived from dialkyl disulfides or alkanethiols were indistinguishable when examined by ellipsometry and XPS; the contact angles of water or hexadecane were largely independent of the oxidation state-disulfide or thiol-of the organosulfur precursor. The rates of formation of SAMs from dialkyl disulfides or alkanethiols were indistinguishable. The rates of replacement of molecules from SAMs by thiols were much faster than by disulfides. This difference in the rates of replacement may account for the large preference for thiols in the competitive adsorption of disulfides and thiols on gold.