Thermal decomposition pathway and desorption of isopropanol (IPA) and tert-butanol on Si(100) were studied using temperature programed desorption. Adsorbed alcohols studied were decomposed into atomic hydrogen and alkoxy on the surface. During heating the sample up to 1000 K, acetone, propylene, and hydrogen were desorbed as decomposition products of IPA on Si(100). Desorption pathways of IPA on Si(100) were largely consistent with those on metal surfaces: beta-hydride elimination reaction to acetone and C-O scission to propylene. For tert-butanol, which has no,beta-hydrogen, isobutene and hydrogen were observed as main desorption products.