The chemical adsorption of 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) has been made on flat oxide surfaces by using two methods of a chemical vapor surface modification (CVSM) and a liquid-phase deposition (LPD) from neat TMCTS, leading to formation of methylsiloxane layers. A remarkable difference in the wetting properties was found for both the samples. Fourier transformed infrared reflection-absorption spectra provided direct evidence for formation of the interfacial Si-O-Si-s (or Si-O-Al-s) bonds and fixation of TMCTS on solid surfaces. Also, it was suggested that a methylcyclosiloxane monolayer (0.49 +/- 0.03 nm) with an orientation of its ring parallel to the surface and the methyl groups outward was formed by the CVSM method, while the LPD method produced multilayers (11.8 +/- 1.9 nm) having a rather disordered molecular orientation. The former monolayer structure was further supported by the molecular mechanics calculation (MM2 force field) on a cluster modeling the TMCTS molecule chemically adsorbed on the surface of SiO2. The difference in the wetting properties could be rationalized in terms of the structure of the layer. Furthermore, a novel method for preparing a mixed monolayer consisting of CH3 and fluoroalkyl groups in the gas phase was presented as an example of the higher functionalization of the methylcyclosiloxane monolayer.