The adsorption of isobutane on a Pt(533) stepped surface has been investigated using temperature programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). Isobutane exists in two monolayer states and one multilayer phase on the Pt(533) surface. The most stable desorption state is caused by isobutane desorbing from the terrace planes. The orientation of isobutane in this state was determined from RAIRS measurements. The second monolayer phase probably belongs to isobutane molecules with only two hydrogen atoms in direct contact with the surface. RAIRS spectra also showed there was little bond weakening due to metal adsorbate interaction.