The adsorption, decomposition and desorption of t-butyl silane (tBSi)(C(CH 3 ) 3 SiH 3 ) on Si(100)-(2 1) reconstructed surfaces was studied with Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy and temperature-programmed desorption (TPD). From the spectra it is postulated that the decomposition pathway is dissociative chemisorption forming t-butylsilylene, with the remaining two hydrogen atoms bonding at neighboring sites. As he sample temperature is increased, the majority of the adsorbed t-butylsilylene undergoes a β-hydride elimination, forming isobutene, which then desorbs. The remaining fraction dehydrogenates and incorporates carbon into the substrate. The carbon incorporation into the substrate was verified ex situ by Auger electron spectroscopy (AES) on a Si(100) wafer after a film was grown with TBSi by ultra-high vacuum chemical vapor deposition (UHV-CVD).