We have studied the chemistry of [(t-butyl)GaS](4) on Si(100)-(2 X 1) in ultrahigh vacuum. The characterization techniques used in this study were Auger electron spectroscopy (AES), temperature programmed desorption (TPD), and low-energy electron diffraction (LEED). Exposing [(t-butyl) GaS](4) to Si(100)-(2 X 1) at temperatures below 700 K gives evidence of gallium, sulfur, and carbon on the surface, as judged by AES, while exposing at an elevated temperature (>700 K) results in nearly carbon free adsorption. TPD spectra measured after exposure at 200 K show that the hydrocarbon ligands of the [(t-butyl)GaS](4) undergo a beta-hydride elimination reaction and desorb predominantly as isobutene. For low exposures, the GaS core of the [(t-butyl)GaS](4) molecule dissociates upon annealing, as judged by the SiS and gallium TPD peaks. TPD experiments conducted after adsorption of more than 20 Angstrom of [(t-butyl)GaS](4) on the Si(100)-(2 x 1) surface show evidence of Ga2S desorption. For deposition at 700 K, LEED shows that the (2 x 1) reconstruction remains intact for low and moderate exposures, and a (1 x 1) pattern develops for higher exposures.