P-31 MAS NMR spectra of trimethylphosphane (TMP) adsorbed on monoclinic zirconia (ZrO2) and on tetragonal sulfated zirconia (ZrO2-S) were measured. The P-31 NMR spectra show that protonic acidity, which does not exist on ZrO2, is induced on ZrO2-S. Lewis acid centers on ZrO2-S are stronger than those on ZrO2. The formation of trimethylphosphane oxide was also detected, indicating oxidizing properties of ZrO2-S that sulfate-free ZrO2 does not possess. ESR spectra suggest the formation of SO3- radical anions during TMP oxidation.