The isopropanol diffusion and dehydration in zeolite HZSM-5 were studied by FTIR spectroscopy. The alcohol dehydration was shown to start at the temperature above 60 degrees C. It was found that at temperatures above 350 degrees C, the isopropanol dehydration was limited by diffusion in the mesopores of zeolite. The method developed allows studying the kinetics of interactions of the reagent molecules with the OH-groups at the external surface of the zeolite and inside its channels.