An AgSiBEA zeolite has been prepared by a two-step postsynthesis procedure that consists of first creating the vacant T atom sites with associated silanol groups by treatment of TEABEA zeolite with nitric acid and then impregnating of resulting SiBEA zeolite with an aqueous solution of AgNO3. The incorporation of Ag ions into the vacant T atom sites of the framework of SiBEA zeolite as mononuclear Ag(I) has been evidenced by combined use of XRD, NMR, FTIR, diffuse reflectance UV-vis, XPS, and TPR. The consumption of OH groups has been monitored by FTIR. The Brønsted and Lewis acidities of AlBEA, SiBEA, and AgSiBEA have been identified by FTIR spectroscopy of adsorbed pyridine and CO as probe molecules.