Pyridine adsorption on sulfated zirconia (SO4(2-)-ZrO2) provides evidence for infrared bands characteristic of both Bronsted and Lewis acid sites. Samples treated at 100-degrees-C retain water and have a higher fraction of Bronsted acidity than when the sample is treated at 400-degrees-C. The fraction of Bronsted acid sites observed for SO4(2-)-ZrO2 is the same in the presence or absence of supported Pt. Based on pyridine adsorption, exposure to gaseous hydrogen at 100 or 150-degrees-C did not significantly alter the fraction of Bronsted acid sites following the exposure to hydrogen.