A study is presented of the amount of coverage of Si substrates by monolayers and multilayers of molecules deposited by the self-assembling technique. Self-assembly was achieved by chemisorption of silane compounds from solutions, on to smooth n-Si substrates. The coverage was examined by IR absorption, wettability and X-ray diffraction. For n-octadecyltrichlorosilane (OTS), prepared as a single layer, the coverage appears to be close to 100%. For a monolayer of a silane-methyl ester, containing 24 carbons (C24SME), the coverage is at least 90%. A film comprising three layers of C24SME molecules could be modeled by a mixture of two- and three-layer regions. © 1985.