A thermophilic alcohol dehydrogenase from Thermoanaerobacter brockii (TBADH) was immobilized by adsorption on Fractosil, methyl-, octyl-, and hexadecyl-Fractosil. As compared to its free form, the thermal stability of the enzyme was enhanced upon immobilization and its pH and temperature optima were altered. The immobilized preparations were used in continuous catalytic operations using a packed-bed reactor. It was demonstrated that the inorganic supports are suitable candidates for operating reactors, especially at high temperatures. Furthermore, larger volumes of the substrates could be converted to a product using enzyme preparations immobilized on the derivatized (hydrophobic) Fractosil, as compared with the unsubstituted form.