Diffuse reflectance FT-IR spectra of methanol and ethanol on Amberlyst 15 and on a synthesizedacidic resin catalyst indicate that alcohol molecules are adsorbed by forming hydrogen bridgeswith the −SO3H sites of the catalyst and among themselves. Some of the alcohol moleculeswere found to be strongly chemisorbed by dissociation of one or two hydrogen atoms. Isobutylenewas also found to be strongly adsorbed by forming a bridged structure between the adsorbedalcohol molecules and the −SO3H groups. DRIFT spectra verified the presence of adsorbed ethermolecules formed as a result of surface reaction and supported a Langmuir−Hinshelwood-typereaction mechanism.