Results from temperature programmed desorption of ammonia, pyridine, and benzene from sulfated zirconia catalysts promoted with Fe, Mn, and Ni are compared. Without adsorbates, catalysts are thermally stable below 900 K. With adsorbates, catalysts decompose partially or completely between 700 and 900 K. It is shown that previously reported conclusions regarding acid strength distributions for promoted sulfated zirconia catalysts that were based on the results of ammonia and benzene thermal desorption studies are likely incorrect because the decomposition of adsorbates and the catalyst were not considered.