In this work organosilicon films are prepared by plasma polymerization and mass-selected polyatomic ion deposition (MS-PID) of divinyltetramethyidisilazane, and by rf magnetron sputtering of polydimethylsiloxane. The composition of coatings is determined by XPS and FTIR. A chemical derivatization method is applied to detect amines in silazane films. Plasma polymers and ion deposited films are found to be more organic; whereas magnetron sputtered coatings are dominated by SiOx species. Plasma polymers are deficient of nitrogen with silicon bound in various SixCyOz species. Silicon in PID-films is bound mainly to nitrogen (SixN). The processes of aging in air or in water are also discussed. (c) 2005 Elsevier B.V. All rights reserved.