Abstract: In this paper, the reversible and irreversible adsorption of isobutylic acid on Fe-Pb-phosphate catalysts were studied by using pulse chromato-graphic technique. The affect of preadsorbed H₂O on irreversible adsorption was also observed. Some information on further consideration of mechanism of adsorption and oxidative dehydrogenation of isobutylic acid on the catalysts was provided.