The use of temperature-programmed desorption (TPD) of isopropylamine (IPAm) was extended to quantify the Bronsted acid site distribution in various modified FAU-type zeolites. We show that while the protons in nonsteamed H-FAU zeolites are distributed evenly between the supercages and sodalite cages, steaming perturbs this distribution by generating nonframework alumina species. Usually, mild steaming reduces the supercage proton density to below 50% of the total proton density. More severe steaming and a subsequent aluminum extraction restore the even distribution.